Full screen video in Firefox

[Neo]

I've come across a strange problem.
I thought not all videos were playing in Firefox.
I tried to watch this video in full screen and it's not possible:

http://www.youtube.com/watch?v=GGvRnExK_qM

But then I discovered that some videos do play in full screen while others don't.
Sometimes I can access the controls at the bottom of the screen and sometimes not.
The cursor changes to a pointing hand and no matter what I do it won't activate any of the controls at the bottom of the screen.
So far I've only noticed this problem with the video linked above.

Any thoughts?