On android quality works but video speed does not.
Also, "Access data for all websites" is a privacy risk. I understand it is required to enable the extension for embedded videos but since this is not the most common use case for many, an option to disable this permission and only let it access youtube.com would be welcome.

Good

Expanded mode does not fill the viewport, "Full page" overflows the viewport cutting off parts of the video, including playback controls and the scrobbing bar.

Pretty handy!! Works on Android too 😁✌️

This addon causes random redirections to Youtube community posts every now and then. Can you please fix it? It's quite annoying.