Not sure what I'm doing wrong, everything's up to date, the extension is activated, I'm logged in and everything...but it just won't fire up on YT.
The Chrome extension works flawlessly for me though.

Gud

Good

Great extension with many useful options to make Youtube enjoyable and usable again.

My personal highlight in v2.0.109: "Restored dislikes count" - thank you very much! :-)

I've used this app for several years, it is loaded with great options for YouTube. I donate $ at least once a year to keep it going and encourage everyone to do the same.