Filmmaker Christopher Knight posts in his blog:
Viacom hits me with copyright infringement for posting on YouTube a video that Viacom made by infringing on my own copyright!

It's a tangled story. From the blog:

So Viacom took a video that I had made for non-profit purposes and without trying to acquire my permission, used it in a for-profit broadcast. And then when I made a YouTube clip of what they did with my material, they charged me with copyright infringement and had YouTube pull the clip.