I also voted it's their right and don't have much to add that wasn't already said along those lines. Like it or lump it, if you don't own the rights or have expressed permission, you shouldn't be using them in your work. So instead, I'll throw out a couple other observations. I'm not so sure it is always about money. I've seen several furry videos that were removed that had short audio and video clips from various cartoons and music (similar to AMVs). One media corporation had them removed, but considering the context in which they were used I think thik it had to do with the company's image than worrying about loosing money. If you consider the thousands of artists the big music companies have on file, it would be near impossible to watch each video and make a case based decision, so they just have a blanket infringement policy to make it easier on them. Which would also explain why memorial vids have been removed.
One other thing that I can't help but laugh at is when someone posts a song, usually the full track, and then puts in the description some sort of "disclaimer" saying it's not theirs and not claiming any copyright infringement. As if that somehow makes what they're doing legal. I had to take a copyright class in college because of my major, but in this digital era where this kind of stuff is so easy and rampent, I'm beginning to think they should include it in highschool courses. Then they'd realize that their argument of "I bought the music, so I can do what I want with it" is bogus.