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: https://cys.mantishub.com/view.php?id=31

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 cytsaver@hotmail.com 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: https://cys.mantishub.com/view.php?id=10
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 either...it 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 cys.mantishub.com/my_view_page.php 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 cys.mantishub.com/my_view_page.php

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 cytsaver@hotmail.com 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 cytsaver@hotmail.com, 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 https://cys.mantishub.com or contact us at our support email (cytsaver@hotmail.com) 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



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.

Rated 4 out of 5 stars

This add-on had worked for me before and I loved it because it was the only one that allowed me to download 480p quality, which is often the highest available.

Recently, 5.5.1 stopped working and I updated to 5.5.3, which appeared to be working fine at first glance. But actually it wasn't. I encounter the following problem: When downloading 480p movies, two temporary files are created, which are supposed to be merged to one mp4 file after the download completes. This conversion fails, the two temporary files get deleted, and I am left with nothing.

I am on a Mac. I have downloaded the FFmpeg linked at the CompleteYouTubeSaver website, so should have the most recent version that is expected to work well. I have located the folder containing the FFmpeg file through the Options dialogue, and this looks alright to me, as the appearance of the dialogue changed in the expected way.

Any idea what I am doing wrong? How can I find out what may cause my problem?

You are not doing anything wrong, a fix is in the works for Mac and Linux problems and should be ready very soon. Please bare with us. Thanks for your review.

Rated 2 out of 5 stars

0 byte issue again with version 5.5.3....

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

Mac and Linux users, if you are still having problems a fix is in the works

Rated 4 out of 5 stars

By far the best YT video saver I've ever used. Tends to work when most others don't, and the use of FFmpeg to allow such a variety of A/V combinations (as well as audio or video online) is sheer brilliance. Hopefully the only YT downloader I'll have have to use again.

My one criticism (for which I sadly detracted a star) is about the distribution and update process. When the program doesn't work (usually due to new YT coding that needs to be compensated for), there's no error message....just a small spinning box, then the menu that appears as normal, and then downloads 0 byte files without indicating why, or even that an error has occurred. Very frustrating interface issue.

What's more frustrating is how these are addressed. Sometimes it takes a week or two for a message to appear on the addon page, saying that YT code changes have necessitated reprogramming. Again, this should be an error message in the web browser itself, when the error occurrs, not something we might happen to see in a week or two.

In my opinion, this plugin badly needs a Github page. That way we could go there and tell instantly what the problem was, what was being done about it, when it might be fixed, etc. Would also make it easier to contact the developers.

Another idea would be to implement a secondary install stream, like Mozilla Archive format's "experimental" stream. I don't really care what the Mozilla add-on reviewers think of the plugins I use! I would love to be able to install directly from Github or the current development page.

Thanks for your constructive review! Secondary install stream and Github page...in the works as we speak :)

revision 5.5.2 removed Rated 4 out of 5 stars

Revision 5.5.2 removed by Firefox,why is that?

Yes, v5.5.2 was reviewed by an editor and disabled. Just a technicality though, they are requesting some more info. Should be up again shortly, please bare with us, thanks.