From the “so obvious I should have known” department.
I was watching a gaming video and the start of the video was really slow. I realised that I rarely fast forward through YouTube videos and when I do it’s with the mouse to skip big chunks of video.
I only wanted to skip the bit about the game menu and the mouse would have been painful clicking on the progress bar all the time. What about the keyboard? I had read that using j and k goes back and forward but it didn’t work for me so I searched for this most obvious of answers and found this page.
J and K still don’t work but right and left arrow do the job and there are also many other controls!