Works like a charm Rated 5 out of 5 stars

Works like a charm, just download the latest version from the link in the description. Thanks, I can download 1080p now!

Thanks for the 5 stars!

Rated 5 out of 5 stars

Really very nice and stable youtube video downloader. Love it :)

Thanks for the kind words, glad you like the add-on :)

Rated 5 out of 5 stars

A lot of options and customisation. Other video downloaders feel too simplistic and basic, and can be quite intrusive by putting their buttons on the webpage. This can be as easy to complex to use as you like.

I do have one request, though. Would it be possible to download a mute video? I use a forum where you can upload mute webms only, audio ones won't upload, and I'd like an easy way to get YT videos in an uploadable format.

Currently there is no official way to download a mute webm video. However for DASH files, if you play the video before the files are muxed, you will get separate video and audio files. Make sure to enable "Open target folder when downloading" in Options>Download tab. Hope this helps, thanks for the review!!

5.6.17 Very good overall Rated 5 out of 5 stars

Great add-on. Many more options than most of the others I've tried, and for this reason it was a little daunting at first. But well worth the time to learn how to use it. Can download and convert to an impressive number of formats.

I've only had one issue. For high quality MP4s it's supposed to merge audio and video after the download's complete, but it's not working for some reason (5.6.17). I'm using XP (no .NET) with "Hide console window" unticked per the instructions, and a recent version of ffmpeg, so not sure what the problem is.

Would recommend as first choice.


I was using FF31 so updated to FF36 and it's working great now. I think part of the problem was my own fault. Sometimes after the download starts I close the browser and just watch the download window. I've got it set to close the download window automatically when the download completes, so after the download finishes and the window closes, the FF process quits and CYS can't run. Duh!

Thanks for the 5 star review!!!

Sorry to hear you are having a problem with CYS. We did receive your email and will be contacting you shortly. BTW, with v5.6.17, you no longer have to unhide the console window in WinXP; ffmpeg should work just fine without .NET framework.

Rated 4 out of 5 stars

A great 'must have', and works fine. (V5.6.3) The only thing I miss it: The possibility of download of the originally uploaded video or the audio track only in its real! format. The application is certainly "knows" that what is stored on Youtube. Why CYS don't tells me? Or if this is in the download menu, how can I choose which is the original? I don't want any conversion! Therefore I rate this 4 and a half star.

Thanks for your review! Version 5.6.3 is no longer working properly. For critical fixes, please download the latest version (v5.6.14) here:

CYS saves AAC/M4A/OGG/OPUS audio tracks without transcoding, i.e. without any quality loss. CYS only transcodes audio to MP3 (and WAV). Hope this helps, please contact us at if you have any other questions, thanks.

Very recommended Rated 5 out of 5 stars

Very good, finally I can download 480p and 1080p videos WITH sound, which I couldn't with flashGot...

Thanks for the 5 star review!!

Rated 5 out of 5 stars

Excellent add-on! Just fix the new problem so everything can return back to normal! :)

Fixed!! Download version 5.6.8 here:

Thanks for your support!!!

v5.6.3 - It works great with PaleMoon25, thanks Rated 5 out of 5 stars

Download 1080p mp4 & webm (H264 & VP9) perfect, but I found 2 small errors:
- It don't found 4K
- It saves 2 audios in a video (in mp4 and in webm)

The missing 4k format is Fmt 266. We added this in CYS v5.6.6.1. You can download it here:

If you have any trouble, let us know and we will email it to you.
Thanks for your review!!!

DownThemAll support? Rated 5 out of 5 stars

Really great add-on. Easy to choose what to download and muxes for me!

Have you thought of adding support for the DownThemAll add-on? YouTube videos download much faster with a download accelerator.

Thanks for the 5 star review!! Here's the problem with DownThemAll and other accelerators. After downloading the separate audio and video streams (DASH formats), DTA would not be able to mux them together. Nor could it be used when extracting/converting audio formats. DTA can not be used for any FFmpeg operations. What we would like to do is add built in mutli thread download capabilities to CYS. Look out for this in the future.

please add support to download youtube 60fps video Rated 5 out of 5 stars

4kvideodownloader able to download 60fps youtube video. but they can't download vp9

This user has a previous review of this add-on.

60fps formats were already added back in Nov:

h.264 720p 60fps = fmt298
h.264 1080p 60fps = fmt299

vp9 720p 60fps = fmt302
vp9 1080p 60fps = fmt303

The latest version of CYS is v5.6.6.1. It can also download Fmt 266. You can find it here:
If you have any trouble, let us know and we will email it to you.

And we haven't forgotten about your request for subtitle downloads is coming.

Hope that you will add that one extra missing star :) Thanks for your review.

Excellent, time-saving download extension Rated 5 out of 5 stars

Love the DASH auto-muxing. The extension works great on YT. There are some minor glitches with Pale Moon, hope this gets fixed.

I'd also love to see it working outside of YouTube, so I can get rid of my other download extension. Also wonder if it's possible for it to *auto*-update to the latest version, since AMO takes so long.

We are looking into Pale Moon issues as we speak. If you haven't done so already, please contact us at our support email or create a new issue at and let us know about the specific problems you are having.

Downloading videos outside of YT is in the works as well as different Auto updating options. For now you can find the latest version at

Thank you for the 5 five star review!!

Rated 5 out of 5 stars

Downloaded an ultra-HD YouTube video with no problems. Awesome! Make sure you get the 5.6.3 or later.

Good to know CYS is working well for you! Thanks for the 5 star review!!!

Rated 4 out of 5 stars

Nice (at least ver. 5.5.3., the version i got here didn't work)!
Exactly what I needed, finally: To download the highest aivailable quality audio and then convert it to mp3 or ogg. In one click, so i don't have that hassle to manually download in mp4, convert it, delete the mp4 file.
An option for id3 tags would be nice though.

Please contact us at with your ideas for feature requests. Thanks for the review!

Rated 5 out of 5 stars

Version 5.6.3 works without problems. With the previous version i had some issues with the download menu not showing up by clicking the icon. It has only one downside: It doesn't work with videos previously unblocked by a tool like proxmate or proxtube. If it would work with unblocked videos as well, it would be perfect. Maybe this will be possible one day? Thanks for the great work, guys!

Thanks for your review!!! Please contact us at, we need links to videos where you wish to use proxmate or proxtube, and we will look into it, thanks.

Rated 5 out of 5 stars

it is AMAZING!!!!!!!!

but so bad it doesn't donwload the ORIGINAL mp4 anymore :(

Not sure what you mean, CYS can download "Fmt 138 MP4 Original 2304p" and "Fmt 272 WebM Original 2304p" (DASH formats). Please contact us at the support email if you need more info. Thanks for the five stars!!!

Rated 5 out of 5 stars

Hi everybody this app does work as intended, please follow the developers instructions as provided on top of this page.

Apparently firefox moderators have stopped the apps latest version for commercial reason, which is pretty sad. Firefox should be more supportive of their addon developers. More than stealing we see this method as a way to save our bandwidth when watching a UHD video multiple times.

Anyway as far is the app is concerned, works pretty well.

Kudos to the developer.

Thanks for the support!!

We have uploaded a new version (v5.6.3), hopefully this one will pass review. You can download it here:

Icon doesn't work Rated 2 out of 5 stars

Clicking on the icon in the toolbar doesn't do anything.

For info, i have already unhided the Console Window in Options> General tab but still nothing happens when clicking on the icon.

I am on windows XP SP3.

Posting bugs in the review section does not help; we need more information. Please create a new issue at or contact us at our support email ( with this information:

-Firefox, FFmpeg and CYS version you are using. Does this happen on all videos or just some? If only some, please provide us with some links, thanks.

CYS 5.5.3 Rated 5 out of 5 stars

Version 5.5.3 was removed from site. I maked a copy of the add-on.
For Windows x64. Just decompress and put into C:\Users\youruser\AppData\Roaming\Mozilla\Firefox\Profiles\????.default\extensions!YRVQEYiD!DAW-KBgRrW5FxWHayFyhu-p9KrXi0rw6nxApKzgr5lc


Version 5.5.3 can be found here:

A new version should be ready soon...thanks for the 5 stars!

Best WORKING YouTube download tool; needs version 5.5.3 and FFMPEG Rated 5 out of 5 stars

Folks, this is the only WORKING app that lets you download full 1080P from YouTube WITHOUT UPCONVERTING FROM 720P. You NEED FFMPEG in order for it to work, and you should also configure the plugin to NOT HIDE the FFMPEG window. Do that and it WILL WORK.


You NEED version 5.5.3 or it will NOT WORK.

In a very sad turn of events, Mozilla, going against its users, has removed version 5.5.3 from their site. I in fact had a Mozilla moderator tell me that he believes that addons like this should be completely banned as he views that this addon is only used for "stealing." Wrap your head around that for a moment. This is also not the first time that Mozilla has removed working versions of Complete YouTube saver from their site with no explanation.

Sadly, it seems there is no Internet link to download version 5.5.3 anywhere else on the net as the developer does not want to set up a GitHub for some reason which would be the best way to solve this problem.

I recommend that you visit the developer's site, and send an e-mail to the e-mail address posted on their front page and request version 5.5.3 from them.

Hopefully something will be figured out soon to support the users of this very useful addon.

This user has a previous review of this add-on.

Thanks for your review, we appreciate the support!! Yes, v5.5.3 was reviewed and removed by an editor. A new version should be up sometime this week. For now, you can download v5.5.3 here:

WORST APP EVER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Rated 1 out of 5 stars

still not working par TWO
ONE STAR or LESS due to incompetence of developer(s)

This user has a previous review of this add-on.