Unless your use of music or performances by others is okay under the doctrine of Fair Use under US copyright law or under comparable provisions of the copyright laws in some other jurisdictions, you need to be sure that you have the rights to use the music in your video. You can do this by getting explicit permission from the copyright-owner or by using royalty-free music.

The sites listed below offer royalty-free music that is totally free - download tracks right away and use without any fee. Please make sure to pay special attention to the stipulations of any Creative Commons-licensed music, as certain CC licenses require attribution to the original author or prohibit commercial use of the material (uploading to Revver is considered commercial use).

• partnersinrhyme.com
• brainybetty.com
• incompetech.com
• jamendo.com
• openmusicarchive.org
• opsound.org
• ccmixter.org
• thefreesoundproject

• stockmusic.net
• royaltyfreemusic.com
• shockwave-sound.com
• smartsound.com
• opuzz.com

Unfortunately, we cannot recommend one of these sources over another but a quick search online for "royalty-free music" should provide you with a lot of options. If you use GarageBand, FruityLoops or LogicExpress software, all three applications come with royalty-free pre-recorded instrumentals in loops.