I'm not one to write reviews often but I feel the need to for this add-on. Firstly, my biggest gripe recently is YouTube's UI "improvements".
This add-on lets me clean up the home page's sidebar to get You(history, playlists, etc) back where it used to be. I then switched Subscriptions to be on a link below the Home link, easing that burden so I'm not hitting a subscription instead of history like I have been lately. Also was able to make the videos and thumbnails squares again, which I love.
I just started playing with the add-on, so I might not have seen it or it might not be possible to do, but the only thing I wish this included so far is to remove the drop-down menu next to watched videos in History and bring back the X that was next to them for the longest time.
Aside from that little thing, I absolutely love this add-on, and the developer genuinely has my highest respect for this. So thank you!

没有UnTrap好用，太简单了

I only got it for the 'Hide watched videos' feature, and it doesn't work.

Much neeeded addon, lets me continue to use the scroll wheel for volume controls provided by Enhancer for YT. Why does Google always have to change the YT UI?

Thanks finally i can turn off this AI retard voice

It doesn't work to hide those dogshit members only videos. Which I'd give anything to make those MFer's gone forever.

It's a cool extension, essentioal with that new shitty UI. But can I ask for you to do something with "add to playlist" option, so you can, as before this new shitty UI, add one song to multiple playlists without the window being closed after each.

Thanks you so muc, hope you will read this.

thank you for taking the time to make this and share it with the rest of us. doesn't seem to successfully block ads though

Works great, especially after YT shit the bed with it's latest UI update. Need to refresh page (as of today) for it to work though. Still THE best extension for Firefox. Thank you!

It ACTUALLY reverts the ugly new video UI back to the way it used to be. That is literally all I needed this for. Good GOSH, I'm getting so sick of having to install a new extension every time YouTube does something...

That being said, I'm also very grateful it's an option available to me, or I probably wouldn't even be on the internet at all any more. Thank you, extension developers, your work is appreciated.

EDIT: Forgot to mention that, for some reason, I have to refresh the video page (sometimes more than once) to get the old UI to apply. Not sure why, but it's worth it, and still better than my previous method of "embed the video into a Tumblr post and just watch it in the 'new post' creator".

EDIT 2.0: It seems like the UI "sticks" when you don't open a new page. Like, say, you have to refresh the page a few times, and finally the extension kicks in, and fixes the UI. Opening a video in a new tab makes the new UI come back, and you have to refresh again, and it's annoying. But if you're in, for example, a playlist, you get to the next video, and then the next, and you're five videos in and hey! You haven't had any trouble with the UI reverting. Nice!

TL;DR: Refresh the page a few times to make the new UI go away, then stay on that page by using a playlist (copy+pasting URLs into the tab doesn't seem to work). I use my Watch Later, because I've already used it as long as I can remember, and it's convenient to just hit the little clock icon and have everything ready to go.

the best youtube extension out there

It rolls back to the previous UI as intended, except for the Like/Dislike/Show Comments/Share buttons that are in the lower-right when the video is paused in Full Screen, controls I couldn't care less about and want blown out the airlock NOW.