Greasy Fork is available in English.
Add speed buttons to any HTML5 <video> element. Comes with a loader for YouTube and Vimeo
< Обсуждения Video Speed Buttons
Try the keyboard shortcuts. They work for me. + - and *. Unfortunately, I don't have time to investigate why the graphical UI isn't showing right now, but I pushed a patch to deal with vimeo resetting the speed.
Broken