Now, in the menu for an embedded video is a “watch in high quality” option. I think this is new. Previously, the only way I’ve seen to do this is by adding bits to the URL of the embedded video. You can test it out here (the option only appears have the video has started playing).

This new option is handy if you want to watch the high quality version without clicking through to YouTube. [Update: CrunchGear verify this is new]