I am really tired of working on videos to post to YouTube only to find months later, if not years later, that someone has placed a copyright claim on them for pictures or (mainly) music. It happens all the time. Then you have to protest to get the ads off your product. It is just nuts. My suggestion is that if you do as I do then you have to keep a record of what source provided you with copyright free music because there are hunters out there that will do this and you may not even be aware that it is going on until you look and find the ads there because they monetize the video to themselves. Just a word to the wise.