HELP! I cannot play video full screen in Vista as I used to be able in XP

Hi, I cannot play the CNBC video (for example,
http://www.cnbc.com/id/15840232?video=275787763&play=1) in full screen
in Firefox or IE. I have a Vista and the default player is also media
player, version 11.0.5721.5154. However I could play CNN video in full
screen on this computer.

In the past, I could play the same videos in full screen in Firefox in
the old computer which I had Windows XP the default player was windows
media player version 11.0.6000.6324

Help Please.