If you look at the video, it seems clear to me that they're using several different kinds of cameras, and several different types of flashes (the silhouettes are not the same).
I guess it's sort of neat, it seems like a really painful & expensive (foolish) way to get this effect. Couldn't you get the same effect for a lot less money by:
1) Not having a camera at all, and just triggering the flashes with a PC cable? (HiViz sells kits that can trigger a flash for ~$20).
2) Not using a flash at all, and just triggering some kind of bulb directly?
If they did this with only 60D + 580EXII, then that's ~$425,000 worth of kit.