Changing photo frame

I still need help with this one:

Does anyone of you know how this guy pulled this off:

http://www.iso50.com/iso50.html

Go to Photography, then a bunch of squares will appear which can be selected…
Now, at first sight, it’s not too hard at all, but here’s my question:

How did he make the black frame under the photos change to the size of the photo every time?
No matter which picture you select, it always sorta flies to the right size and even has a little ‘jumpy’ effect to it.

Does anyone know how he did it?

Thanks a lot.

  • El_Thierro :rambo: