Big spaceship thumb transitions

ok, go to http://www.bigspaceship.com/ and watch the featured thumbnail as it goes from one slide to the next.

i want to learn how to set up advanced transitions like that, but i have no idea what’s involved so i don’t know what i need to learn. i saw someone do something similar and they said it was a scripted mask - but is it just a (bunch of) shape tween(s) and the scripts handle loading the next image over top of the pevious? (i’m good for doing that, the transitions between slides are just weak).

i wasn’t sure where to put this, so appologies if i put it in the wrong spot.