How did they do this?!

[xtremeness316]

I am just wanting to know how the guys at WWF.com did this. Look for the the first bit, the bit with the WWF logo that fades in then out but not normally. You'll see what I mean anyway, any idea how it works?! Reply below

http://ursstuff.wwf.com/IWG/iwg.html

[sfa]

it is just a simple mask moving on top of the logo.

SFA