Yes, Garage Band music is okay.
Here's the official release from LEGO:
From LEGO Group
Creators can submit original videos until the deadline of August 5, 2011, for a chance to win exclusive prizes sponsored by the LEGO Group, like collectible LEGO sets, premium LEGO Universe memberships and more. Winning submissions will also be screened at the Build-a-Brickbuster Pixelfest in Broomfield, Colorado on August 13-14, 2011, and will be included on the Bill Plympton Presents Tinsel Toys DVD later this year.
Anyone can enter the contest, regardless of event attendance, but Denver locals will definitely want to put Pixelfest on their calendar. The two-day event will feature some of the world's best brick flicks - not only from finalists and winners of the Build-a-Brickbuster contest, but also from talented local animators, machinima club members, students and professors at the Art Institute Denver and ASIFA Colorado, and more. Key members of the award-winning LEGO Universe development team will also be in attendance for questions and discussions.
"Many animators get their start by using LEGO bricks to get their feet wet in the world of stop-motion animation and machinima creations. This promotion is our way of giving the creative communities out there an opportunity to showcase their greatest talents," commented Dylan Krider, Pixelfest Producer. "When players aren't busy battling to save imagination in LEGO Universe, they can bring their wildest creations to life with virtual building and behavior tools that make it simple for anyone to make their own machinima creations."
Looking for a little inspiration? Check out these LEGO Universe machinima videos! www.youtube.com/user/ultrahypnotoad
Start making your LEGO machinima masterpiece now and submit before the early August deadline! There are three easy ways to enter - upload videos to www.buildabrickbuster.com/submit.php , email links to [email protected], or mail submissions to the contest organizers.