Music is such a big deal, I’m sure you have watched a movie.
If you are going to submit to festivals or even upload your video to youtube you should own the rights (or at least festival rights) to that selection.
Your choices:
-Find someone to compose and preform a new piece of music. (try colleges)
-Have someone preform a classical piece of music (from a WAY dead composer) ((remember the music might be in public domain but the performance probably isn’t))
-Buy royalty free music, for a set price you may use a piece of music without have to pay performance fees.
I used Shockwave Sound, they have about the best prices. I listened to EVERY piece of classical music they have, it took me a week (at work MUAHAHAHA) and I only found a handful of songs that met My needs. Music is tough because it is so important.
The company’s that I listed for Sound Effects also sell music by the track and CD and just search Royalty Free Music and you will find tons of sites (prices will widely vary).