Found a way to control playback on Youtube website
By Walei, 16 October, 2012
macOS and Mac Apps
I'm not sure if anyone's posted about this already but I stumbled upon some keyboard shortcuts to control playback while playing a video on the youtube website. This is using Safari on Mountain Lion with quick Nav off. The voiceover focus has to be inside the webpage. As long as you interact with the html content it should work. J is rewind, K is play/pause, and L is fast forward. These commands don't work during advertisements by the way. I've only tried it with a couple of videos. Can other people try and confirm that it works for them as well?