almost perfect just a suggestion Noté 4 sur 5 étoiles

You're missing an option to use mp4 (h264) as the preferred format
while google prefers mp4 on windows vista+ it forces webm on Linux's

there are several reasons to prefer h264 instead of vp9 as:
#1 hardware decoding only recent and expencive gpu's have vp9 hardware decoding while 10 year old gpu's can decode h264
#2 Video quality
this is subjective but imo there is a lot less pixelation and ringing in h264 compared to vp9
#3 File size
mp4's are 5-10% smaller then the equivalent webm files

afaik hardware decoding is done by the backend ie ffmpeg
(gstreamer was dropped by mozilla) I might be wrong but I do belive ffmpeg does hardware decoding if your hardware supports it
only new nvidia chips have partial vp9 support 960 and above (titan X has full)
and on intel's side partial vp9 support was introduced with the Skylake processors (full with Kaby Lake)
only a fraction of desktop hardware has vp9 support
regarding vp9 30% smaller lol that's google propaganda for example at 360p
the mp4 is 40.7M
the webm is 53.2M and is 7% bigger
I am using this script to get the file sizes
it doesn't get webm's at higher res I'm not sure why

still I think it's google's bug if it sees Linux in the browser user agent it prefers vp9 I ended up disabling webm
but I think you can add an option to prefer h264

While I agree that some older systems might have problems decoding high-res VP9 videos, the same is true for H264, as firefox currently does not support any video hardware decoding on linux [1]. And when comparing decoding speed, VP9 is typically equally fast when comparing videos with the same quality, because in VP9 they then need a much lower bitrate [2, section "Decoding speed"].

This is also the reason why VP9 videos on youtube are in every case I have seen smaller than their H264 counterparts, usually around 30 to 40 % (you can easily check all available resolutions and their sizes using youtube-dl).

But like mentioned in the description, if you really want, you can control WebM/VP9 with the media.mediasource.webm.enabled setting in about:config. Note that the youtube html5 test site has a bug in that it shows VP9 as enabled even if it is not, however it falls back to H264 when actually playing a video.


I did a test and VP9 and H264 decoding resulted in exactly the same CPU usage on my system. about:support also tells me under "Hardware H264 Decoding" that it is not supported, even though it uses ffmpeg as backend on my system as well.

Regarding the sizes of the video you mentioned, this is what youtube-dl tells me: (excerpt)
243, webm, 640x360, DASH video 457k, vp9, 24fps, video only, 21.59MiB
134, mp4, 640x360, DASH video 606k, avc1.4d401e, 24fps, video only, 24.65MiB
244, webm, 854x480, DASH video 823k, vp9, 24fps, video only, 37.29MiB
135, mp4, 854x480, DASH video 1112k, avc1.4d401e, 24fps, video only, 46.88MiB
247, webm, 1280x720, DASH video 1635k, vp9, 24fps, video only, 73.36MiB
136, mp4, 1280x720, DASH video 2206k, avc1.4d401f, 24fps, video only, 81.69MiB
So VP9 is smaller in every case there as well.

The difference you see are these non-mse files:
43, webm, 640x360, medium, vp8.0, vorbis@128k, 53.23MiB
18, mp4, 640x360, medium, avc1.42001E, mp4a.40.2@ 96k, 40.73MiB
But the webm file in this case contains VP8 and not VP9 and a higher bitrate audio track, so naturally it is larger.

Regarding a setting to disable VP, what is wrong with media.mediasource.webm.enabled?

Some new problems with other add-ons in latest version Noté 3 sur 5 étoiles

(Response to my previous rating and the dev comment)


It seems that with the latest version there are some problems with /some/ videos which do not start uninitialized in conjunction with the FlashStopper add-on;
You mentioned that you redid the "Start videos paused" option (which indeed seems to work more reliable now when enabled) but since it still displays an ugly black screen (and also initializes the video in the first place) I chose to set it to "Never" and let the "FlashStopper" add-on do this instead.

Unfortunately I think the redone option messes with FlashStopper as they might be accessing the same variable and override each other or something so that some videos start uninitialized (the way I want it) while others start playing right away (which is somewheat annoying).

Would it be possible for you to add an option to start the video uninitialized (with the thumbnail and play-button in the middle) instead, even if there hasn't been much demand for this yet, as you said before?


The same goes for when the video has finished: In that regard the "Prevent autoplay of recommended videos" option is nice but it should not remove the thumbnail in the background and the recommended video tiles that appear when pressing cancel on the autoplay without this add-on.


I'm not sure that the "Video playback rate" option is needed since the HTML5 player on YouTube already has that option built-in but it's only used once every blue moon.


I like the new "Video volume" option however, since I like to keep the volume at 50% so I have room to go up or down. So it's nice to have the 50% value in there. Although I think other people might find the rest of the values a bit sporadic. I don't think I remember any add-on with a slider (for precise percent values) on the options page within the about:addons page (maybe not even add-ons which open their own small options window) so I'm not sure whether this would be even possible. Alternatively I'd suggest to make the values go up in 10% increments instead. Or a numeric input field which get's clamped between 0 and 100% if that's possible.


Keep up the good work! ;)

Cet utilisateur a une revue précédente sur ce module.

Thanks for your response! (you can also send me an email or open an issue at github if you like)

I am not sure how the new "start paused" option could interfere with FlashStopper, as it literally does nothing [1] when the feature is not enabled. Does this always happen with the same videos? If yes, could you send me an example? I will have a look at a hypothetical "Start videos stopped" option for the next release.

The "Prevent autoplay" option does exactly the same as the slider that is present on every youtube video page by default (by sending the same cookie that youtube uses to store this setting), so if this results in the recommended video tiles in the player being hidden, this is likely a bug of youtube or another extension.

The playback rate, volume, hide annotations and prevent autoplay features (which are all available directly through the youtube interface) are mainly targeted at users who regularly delete their cookies and so loose their settings.

I tried to make a compromise with the volume levels, because a slider or a numeric field with +/- buttons is unfortunately not possible. I don't like simply putting a textbox there, however this may be nonetheless the most practical solution, we'll see.


Convert to non-sdk Noté 5 sur 5 étoiles

Hi. I use the Pale Moon browser and version 27 will make jetpack/sdk extensions not work. I love this extension and would love to continue to use it. Can you please convert? Thanks!

Cette critique concerne une version précédente du module (3.0.3). 

That is really unfortunate, as the addon makes heavy use of some add-on sdk features.

What do you mean with non-sdk? A classic restartless XUL extension or a WebExtension? As firefox is working on dropping XUL support, I won't convert the addon to the former, sorry.
However as the APIs for WebExtensions become more complete, I think I'll try porting the addon to it. I am not sure what Pale Moon plans to support in the long term, but it currently seems they won't support WebExtensions any time soon.

Having said that, it is certainly *possible* to convert the addon to a classic XUL addon, I just won't be the one doing it. But if anyone wants to try that, I will happily answer questions.

Nope Noté 1 sur 5 étoiles

Doesn't work. Turned all my videos black instead. I can't find anything that actually works.

Cette critique concerne une version précédente du module (3.0.3). 

I am sorry that it does not work for you. You can open an issue at github ("Support site") or send me an email if you want and I will try to help you debug this problem.

Some information that would be useful are the version of the addon, os and firefox you are using and if you have flash installed and/or enabled.

You could also try the new beta version 3.1.0 beta 3 ( and see if it works with that.

Thanks Noté 5 sur 5 étoiles

perfect to pc low very very low

Cette critique concerne une version précédente du module (3.0.3). 

Noté 3 sur 5 étoiles

I had some problems with this. It worked sometimes ... and sometimes didn't. Good idea, though.

Cette critique concerne une version précédente du module (3.0.3). 

Could you be more specific about the things that don't work as expected?
I also just uploaded a new beta version that fixes some long-standing problems, see here for details:

Great! Noté 5 sur 5 étoiles

It's working.

Cette critique concerne une version précédente du module (3.0.3). 

Wonderful! Buh-Bye slow and crashy FlashPlayer. Noté 5 sur 5 étoiles

Since Macromedia convinced coders that Flash was the future, I have hated it. It's slow, crashy, and just plain annoying. This add-on is fixing my internet experience. I only wish it worked on everything flash!

Cette critique concerne une version précédente du module (3.0.3). 

Not tech-savvy Noté 1 sur 5 étoiles

Don't know enough to configure and maintain an alternate OS, and will not spend more money on Microsoft product.

The lack of support for XP is understandable in context but disappointing.

It's good to be one day closer to death.

Cette critique concerne une version précédente du module (3.0.3). 

I can understand your anger, but this is a firefox problem. Firefox does not support H264 under windows xp, because the H264 codec is only built into windows since vista.

Although this might seem as a strange advice, you could try chrome which seems to support h264 under xp as yet.

Edit: It seems Firefox supports VP9/MSE under Windows XP, which should make YouTube work without problems.

Very Good Noté 5 sur 5 étoiles

Very good add-on , integrates well with YouTube and is light on resources, but icon's missing from add-ons manager(at least for me) and needs volume control. Thank you.

Edit: Glad to hear about the icon and yes that's what I mean by volume control, I think it would be useful especially with headphones. Again, thank you for all your efforts.

Cette critique concerne une version précédente du module (3.0.3). 

Yup, the icon went missing when I switched to the new packaging tool with the last update. Should be back with the next release [1].
I am not sure what you mean by volume control? Do you mean forcing other levels than 100%?


Edit: Extended volume control is now implemented in 3.1.0-rc1 [2] and will be part of 3.1.0.


severe jitter on fullscreen view. Noté 1 sur 5 étoiles

severe video jitter on fullscreen view. No better than default youtube player.

Cette critique concerne une version précédente du module (3.0.3).  Cet utilisateur a une revue précédente sur ce module.

There seems to be a misunderstanding here. My addon forces (i. a.) the use of YouTube's own HTML5 player for people which normally get the Flash-based player. It does not include it's own player.

It is hard to say from here where your playback problems might come from, but old Firefox versions, disabled hardware acceleration or broken graphics drivers often cause problems with video playback.

Wonderful Noté 5 sur 5 étoiles

Sometimes it even allows to save videos in resolutions not allowed by flash addons. F.e.

To save any video:

click the small icon in the address bar, just before http://

click "More information"

click "Media" tab

you will see a long list of files but only one says "video" in the "type" column; click on that one;

click "Save As" then change the extension to .avi;

Thanks for the GNU licence!

Cette critique concerne une version précédente du module (3.0.3).  Cet utilisateur a une revue précédente sur ce module.

Thanks for your review!

Another great tool for downloading videos from youtube is youtube-dl ( It also supports downloading videos that use MSE, which you cannot save using the browser directly.

The developer is great! Noté 5 sur 5 étoiles

Unfortunately, it's only working function is HTML YouTube player (who would have thought, yeah?), but function "auto pause" does not, also "Disable Flash on YouTube" has wrong name , it should include "only" like "Disable Flash on youtube only". Also there is no "disable annotations" function.
I look forward for fixing those tree mistakes, thanks for reading.

UPD1: Got your answer. Well, I did mean that disabling Flash can cause it's disable also on other websites, not only YouTube. This option disables Flash ONLY on YouTube, right? So call it so please, if I'm right.
Nope, restarting the browser didn't help, unfortunately, still using YouTube CC addon.

UPD2: Now it works properly, thanks for your time and efforts. 5 stars to Griffindoor!

Cette critique concerne une version précédente du module (3.0.3). 

Starting videos paused can sometimes be a bit buggy, but generally it works fine for me and most users that I talked with. However sometimes you have to restart your browser after you enable this option (or any other option, see the description). I will see if I can find a workaround for this in the next version.
I am not sure what other meaning "Disable Flash on youtube" may have, so I thought this was unambiguous until now. What did you think it meant?
An option for disabling the annotations will be added in the next update ( If you have a youtube account, you can also disable annotations in your personal settings.

I would recommend you contact me via email for further discussion, because the review system here is very limited.

thanks very much Noté 5 sur 5 étoiles

good it fix my error script stopped responding for you tube :)

Cette critique concerne une version précédente du module (3.0.1). 

Great Addon Noté 5 sur 5 étoiles

Really nice - works perfect and saves a lot of time

Cette critique concerne une version précédente du module (3.0.1). 

Nice Add-On. This is Add-on not plugin id***s Noté 5 sur 5 étoiles

Nice Add-On.
@DarylWise1 this is Add-On!! Plugin is Flash Player, Quick Time plugin, Real Player... Plugin is installed from installer from QuickTime, RealPlayer and other software. This is difference noobs.

Cette critique concerne une version précédente du module (3.0.1).  Cet utilisateur a une revue précédente sur ce module.

Finally A YT Plugin That Does All I Need! Noté 5 sur 5 étoiles

When I watch videos on YT, I like the video to automatically play at the highest resolution available (except 4K and beyond because I don't have 4K capable hardware) and the theater mode to be enable. I have been using a plugin for a few years now (which will go unnamed because the developer doesn't listen to customer feedback/bug reports) which did do that up until the beginning of the year. Now that plugin fights with HTML5 and when you try to enable the feature to have videos auto play in theater mode, the video gets all messed up and it does not save your configuration of having theater mode enabled at all times. But thankfully, this plugin not only puts videos in 1080p (when available) automatically, but the theater mode actually works!! When I close my browser, re-open and go to a YT video, theater mode is already enabled!! Yes!!! I highly recommend this plugin!

Cette critique concerne une version précédente du module (3.0.0). 

Annotations Noté 1 sur 5 étoiles

There is no way of disabling these annoying annotations!

Cette critique concerne une version précédente du module (3.0.0). 

There will be an option to hide all annotations in the next version 3.1.0:
Unfortunately I cannot tell you an ETA yet, but it shouldn't take too long.

Clipping, no volume control - set too loud! Noté 3 sur 5 étoiles

Volume control nonexistent, 'clipping' of loud signals in many videos makes speakers pop and click at high frequencies. Same problem with other players after upgrading to this version of FF. Nothing to do with either computer audio or amp settings -happens at any device or amp volume. Clipping could be caused in other previous players when slider manually set too high. Now it is an annoying and dangerous default for speakers. If slider is disabled, please at least have default set to 75%, not full blast.
Firefox ver=38.2.1, player ver=3.0.0, OS=Solaris11.2, o/p.device=OSSv4AudioMixer, o/p.hardware=RealtekALC885codec, cable=S/PDIF, amp=integraDTR20.2, spkr=psbImagine.

'Fix ...bug...' button has no effect on the slider or volume, whether checked/activated or not. That is something I saw and tried before; still has no effect now.
Edit (2015-09-29): Slider widget always becomes visible on hovering and can be visually manipulated, even visually muted, as expected. But that still has absolutely no influence on the 100% volume level of youtube transmissions, regardless what position it is visually set to.

I agree there is a disconnect between the slider widget and what the addon is doing, and regardless of the setting of the 'Fix...bug...' button. But that's part of the problem, as there is no option or way to reduce the destructive 100% volume setting to something less.

Cette critique concerne une version précédente du module (3.0.0). 

Please apologize my late reply.

You are right, if "Fix volume bug on YouTube" is activated in the addon settings, the addon sets the volume to 100% at the start of the video. However if this option is not activated (which should be the default after installing the addon), the volume of the video as set by youtube is not changed in any way.
Have you disabled this option?

Edit (2015-09-28): So you mean the volume slider is not displayed at all for you? It appears for me if I hover the speaker icon ( I have no idea what could be causing this, as my addon doesn't fiddle with the slider at all.

Edit (2015-10-08): Hm, this sounds like a bug in the youtube player or in firefox. I can send you a test version of my addon that sets the volume to say 50%, but I am not sure that this will solve the problem. Just write me an email to if you want to test it anyway.

Not activating at all Noté 4 sur 5 étoiles

Seems that there is an issue

Even if I set my default resolution, size and method, the Addon never loads it, even on videos that allow the resolution

Is there a way to clear up the setting. FYI I tried uninstalling but didnt work

Cette critique concerne une version précédente du module (3.0.0). 

You can reset the settings in about:config, they use the prefix "extensions.jid1-qj0w91o64N7Eeg@jetpack". However at least the player size should work regardless of the loading method you choose. Does the small button of the addon appear in the top right corner of the youtube site? Which firefox version do you use?

You can contact me via email if you want.