Having problems clicking on flash videos to play, skip or pause them? This is a documented bug and it seems to effect those who are running flash with compiz enabled.
A quick and dirty work around
This sounds lame but it worked for me. If I right-click and hold the right mouse button while clicking on the flash video; play, skip and pause suddenly work. As soon as I let off of the right mouse button it doesn't work. I tested it in Chromium and Firefox.
This is not a solution but I hope it helps.
Running: Ubuntu 9.10 AMD64 with adobe flash player 10