Works great but it does not work while using a User Agent Switcher which is a bit sad since youtube is close to unusable without one to fake Chrome.
And using youtube without this extension is also awful nowadays with all those shorts taking up space.

It seems a glitch deleted my review so I'm reposting to keep users up to date.

Used to be a great extension, almost mandatory. Unfortunately there seems to be a problem that's causing some users to be unable to update to the newer version of the extension (trapping them on version 2.0.121) and this older version is starting to not work anymore. It's probably a good idea to not install until the problem has been fixed.

I'm in currently talking with the dev team via email to find a solution (future update, about:config edit, "unpacked extension") but communication seems to be tricky. I'll update this review when i have confirmation on a fix.

For years this extension worked very good. Lately or a week now, its working in part. I can control the volume with the mouse, but the Video player Control disappeared. I tried uninstalling, re-installing, clear cache, reinstall firefox and then redo everything, still the issue the is same. Basic features disappeared or are not working. I read reviews here, some comments talk about this but not similar issues.

It worked fine for the first time, than disappered for some reason if reload the site.
Totally fine in private mode DKW.
PS. Tried disable others addon or install previous version. No use.

I love it, youtube videos that starts at a low default volume instead of blasting me out of my seat. Awesome !

Quite enjoy this extension. I have noticed the button for rewinding the video to the left of the pause button remains visible for me even when the video bar hides, though it could be due to my many other youtube visual scripts. Also the older update had a much less noticeable opaque box behind the controls that I preferred; an option to adjust the opacity like with the cinema mode would be nice.

Been using this for years, a must-have!

One recent bug - occasionally when using the playback speed wheel while a video is playing, then navigating to another open browser tab, the video will return to 1x speed and won't be able to be altered without refreshing the page.

Good for everything, only issue is that on every device i've used the firefox version on the audio breaks above 8x speed

Edit: All of my issues have been fixed so I am changing the score to 5.

Missing "Videos per row" feature!!
Please add the "Videos per row" option (under Appearance) to the Firefox version! It works great on Chrome and it’s the only thing missing here.

Never had a problem with the extension until now, since the last update when i am in full screen mode the video isn't taking the full screen space (3840*2160) , instead i have a grey border that i can't seem to remove.

Edit: Changing my review to 5 stars because I now think this issue comes from Youtube itself and not the add-on

Beside this issue the add-on is great, as i said never had any problem for years before Youtube decided to mess up the UI.

Thanks for great extension. Thanks for returning to firefox addons portal. For those who are having trouble with the extension, please check if the "User Agent Switcher" extension is installed - they do not work together.