When uploading a video to YouTube, most people like adding music to go with their imagery. Well, unless you own the rights to the music, you need to get permission. I heard someone say, "No problem, I'll just get my friends band to do a cover song". Although, I do enjoy cover songs immensely, you still need permission from the original author to use it. Good ole copyright law getting in the way again. If you turn the tables and you are the artists, you're pretty happy about that right now.