I wanted to get this stock footage pack (http://www.tubetape.net/servlet/the-186/Explosions-cln--FXhome-Stock-Footage/Detail) for my friend who is into making movies. I was wondering if the pack was compatible with iMovie. The link says that the footage is in NTSC and PAL formats but I don't really know what that means. Can iMovie use that format? And would the images remain pre-keyed (I assume that they are already pre-keyed)? Thanks for helping this newb!