Multi-monitors and fullscreen Flash video
This is particularly annoying in a multi-monitor scenario, where you may want to use one monitor for video playback. Clicking anything outside the flash window will exit fullscreen mode.
So far, solutions to this problem have involved direct hacking of the Flash binary ( http://www.youtube.com/watch?v=qwH_-C2-93E ), but it won't work on the long term.
So any other suggestions?