Cannot select video quality

Cannot select video quality, because the Youtube controls are hidden. For me, the videos are always shown at 240p, which makes screencasts completely unreadable. I ended up lookup up the videos and watching them directly from Youtube.

Note that forcing the highest resolution is not a solution: I have a slow connection and can only watch 480p realtime. For some screencasts you need 720p to make code readable, but then I need to prebuffer the video.