I know I used to be able to watch Flash material (like YouTube movies)
in full screen, but I am not able to any more. When I go to full screen
I have a black screen with sound. When I click "Esc" I go back to
windowed viewing without problems, but full screen is not possible. I
have tried with different browsers: Opera, IE, and Safari so the
problem seems to affect both the Active-X and the stand-alone version
of the Flash plug-in. I am running Windows Vista Ultimate on a HP
dv2550se laptop.
Try hovering over the video and right clcking.
Pick settings and uncheck enable hardware acceleration.
It's a quick fix if it works. Might want to check for new
graphics card drivers too.