Oh, that was well done. I think they probably used key framing to move, or zoom in/out, the images. There's an apple software called Motion that will do that - I've played with it, but haven't spent enough time using it. I think you can create the effect directly in FCP, too. I don't know about iMovie.
:/


Like seekingferret said, I have used dropbox or google drive - those are both free. ;)