Crazy Masking thing

I was looking around at different flash sites and I came across this cool cs site, and I noticed the flash on his goggles. I dont really know much on masking, which I think thats what it would use… Any input?

yep, it’s masking alright…
make a rectangular fill. Change it’s color to linear and make it so that you have 3 gradient pointers there. Ãhange the color of the first on white and change it’s alpha to “0”
Change the middle ones’s alpha to 75 or so and make also white.
And for the third the same as for the first.
Convert it to a movieclip and animate it to move from left to right.
add a new layer and draw the are where you want it to show the anim (in this case the goggles) and make the layer a mask.
That should be it! You can experiment on your own now.

Thanks alot, that helped. Not to mention it cleared some issues up that I had with masking.