How to get this shape effect

http://www.rage.com.br/

How the white shape is animated and drawn along the top?

I made a similar thread to this but i don't think it would be the same effect

Thanks!

this shape...

i think masking is used

im a complete n00b and dont know what masking is.. any links to a tutorial or anything?

there probably is but here`s how u do it:

u`ll have2 layers. on the second one u`ll have a picture or a shape (ex: the white shape from that site)
on the first layer u`ll have a shape, convert it to graphic and than insert a few frames on wich make a motion tween, that makes the graphic move over the pic. now on the first layer wright click and mask.