* Person A composes some music, releases it as CC-NC
* Person B uses that music as the background to a home video, uploads it to youtube
It seems like B is following the CC-NC license? So then A goes to YouTube and, via Content ID, says "I own the music B used in their video, they didn't have permission to use my music, but I'm willing to let them use it if you put ads on their video and give me a cut".
(Again, I do work for Google, on unrelated stuff.)
