I've tried other highly Youtube improvement extensions here on add-on store. While this has less stuff you can do this does have what I mostly wanted. A big reason why I prefer this over others is while you can't customize the site. This extension hasn't once frozen my videos or randomly stop playing them while I multitask on other tabs witch frustrated me about them. I applied the same settings I was allowed to this extension and still no problems. If I could ask for 1 thing I would wish for a Sound Booster. Overall i will continue to use this and hope updates do continue.

did not actually work. videos still loaded at normal size and 360p despite my settings saying theater mode and 1080p

doesn't change videos to high resolution.

I've tried a every couple of months for past few years, never worked. I use stable branch.

Not working

Is not currently working on mobile Firefox Nightly.

Doesn't actually do anything to youtube videos.

Not work anymore, even update not helped

It doesn't work on Android