Yes. I got an e-mail from someone who said to check something out, so I went to YouTube. I had written a theme song for a kids' show, and there were more than many versions of little kids and teenagers performing this work on YouTube. The parents had posted it and the kids had posted it. I have no problem at all with those users generating that content and putting it up there. It's the aggregation of it and the monetization of it in some forum so we don't get our content.
As far as the mashups, where you can define what is a mashup, etc., I'd have to leave that to different definitions.