It's great and all, but it breaks embeds on speedrun.com

this would be perfect but it doesn’t change the UI at all, it works on google but not when i move to Firefox and the experimental features are nowhere to be found

Works fine but like Firefox user 12726217 said its now giving "Playback isn't supported on this device." errors or nothing at all(just a black area that you cant interact with), but it seem to mainly be on embedded videos, sometimes video works after several refreshes, but like 90% of the time it gives the playback error or its just a black area. Disabling the addon makes videos load with no issues.
Edit: Works fine after new Update

Normally a good addon, but Google seems to have started to block it the last few days. With this addon enabled some videos now give an error saying that playback isn't supported on this device.

great and useful extension if only it doesn't cause interruptions. it takes seconds before the video loads and triggers "experiencing interruptions?" popup from youtube

Proprietary but no bigger/better toolbox available

works really well and has pretty useful features

Really solid extension. Clean and lightweight, fits perfectly into my workflow. Does exactly what it promises.

Good extension, BUT: recently YT won't load video player while this extension is working. I'm not sure who's to blame for this, leaving review because I wonder if other users have the same issue.

Recently the automatic video quality selection has stopped working.

This add is so good ... it have so many options I need to explore them ... but basic one are doing job for me.