As others have reported, this no longer works and just shows a waiting spinner. This applies to Firefox 78.5ESR as well as 82 and is not fixed by downgrading the add-on (tried the last 2 and 0.2.9, which used yo work), so may be due to changes by YouTube. Please update to fix, thanks.

Does not seem to function in Firefox 82.0.2. The download button appears beneath videos, but when clicked it's simply replaced by an endless spinning activity indicator, and fails to progress beyond that point.

Worthless; just garbage.

very simple and useful for songs only audio downloads, but hope there will be save as dialog for firefox soon...err...actually does not work at all, waiting animation displayed in place of button, i don't think this is interference of other extensions like ad blockers, useless, does not work

Скачивает пустой файл

Does not work! The dialog box under video shows only "?" instead of file size, when trying to reload with all antitrackers disabled it only detects icon size ( 2kB) on all offered files.
The screanshots are out of date showing the earlier version and do not depicts the truth.
It was a great add-on when it was one exrension with audio converter and muxer which is mentioned and links are provided.
Gave a single star for developer to take more attention to what people say and fix the problems that seems to continue more than a year now!

ne marche pas avec par exemple https://www.youtube.com/watch?v=Hi7Rx3En7-k

Doesn't work. Never starts to download.

clicking the download arrow just shows a loading spinner and does nothing! not working

Don't work

Stopped working