I'm late to the new BG series, catching up with the help of Netflix and what little spare time I have right now. It's a compelling show, with amazing special effects and good writing.
Now, the producers have created the Battlestar Galactica Videomaker Toolkit, a collection of video and audio clips from the show that you can use for free to create your own BG movies. If you're looking for some footage to experiment with in iMovie, this looks like a fun start. When you're done, upload your clip—the producers will choose their favorite clip and broadcast it during an upcoming episode.