Where to find Creative Commons, Public Domain, and other "rights free" or "rights-light" audio material.
How to get royalty-free music and sound effects to add to your videos for free in YouTube's Audio Library.
Replace your video's soundtrack for free with a song from YouTube's library of thousands of tracks. To try it out, go to your Video Manager, select Edit, select Enhancements, then select Audio.
Vimeo provides an easy way to quickly find Creative Commons licensed audio tracks to include in your videos. When searchiing the Music Store, toggle on the "License" drop-down menu that allows you to filter on all or a particular type of Creative Commons licenses.
Creative Commons licensed image by Flickr user Colleen Greene.