Just like how Twitch gets better with FFZ, YouTube gets better with the Enhancer.
This add-on gives me a solid feeling of having control over the interface.

Disabled. Doesn't block ads on Youtube. Made sure it was enabled in Addons. I had all but the optionals enabled. Youtube still keeps kicking over to ads.

Sometimes I can't change the speed for the first video I open, it onlys shows xNaN, but reloading fixes the issue. - like said other users

Very nice to have to extend YouTube. I install this on all my machines

uninstalled. butthurt developer that can't take criticism. For everyone having received the same fate (know for a fact there are more), i found alternatives in the greasefork community.
plus, currently bugged anyway (march 2021)

Fantastic set of tools, a must-have for YouTube on desktop.

Sometimes I can't change the speed for the first video I open, it onlys shows xNaN, but reloading fixes the issue.
Apart from that, a very nice extension with lots of options

I started using it for its loop tool (which works flawlessly) but then started using more and more of the many tools available, like default resolution (super handy), detachable player, ad controls etc. Excellent Firefox extension.