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.

Nice job. Lots of options to play with.

creo que el mejor add-on para youtube, aunque recomiendo un addblock de toda la vida para el tema de los anuncios

By installing this extension you can make Youtube - Youtube pro max advance ultra