How would you create something seen here?

http://mullerphoto.com/

i know it has something to do with embedding a layer over a layer but thats about it.

any and all help would be great.

Leaving out the fact that the pictures change which im sure you can do on your own:


You have layer1(a mask layer) which has a rectangular MC (at least the size of the pictures) which is always moving to _xmouse, _ymouse

You have layer2 which is the picture on top (masked by layer1)

And you have layer3 which is the bottom picture (not masked)