Filmmaker Christopher Knight has prevailed against Viacom by filing a counterclaim notice with YouTube:
VIACOM SITUATION UPDATE: YouTube has restored my clip

Knight goes on to say:

Very special thanks to Fred von Lohmann and the Electronic Frontier Foundation for their terrific assistance in this matter! Folks, I cannot begin to describe how impressed I have become with the Electronic Frontier Foundation because of this. Theirs has been the kind of service that is so rare to witness nowadays that when you do see it, it practically comes as a shock. There's no telling how much grief and headache that Fred and his crew have prevented not just for me, but for a lot of other people also. And if you find that you are capable of doing so, I would really like to suggest making a contribution to the Electronic Frontier Foundation. This is one organization that really does merit a tremendous amount of respect for the work that it does.