Dear Rich: Can you check out my video and let me know if I can get fair use?
We can't tell whether your video qualifies as a fair use because Viacom has "blocked it on copyright grounds." We also can't tell you the basis for the YouTube takedown -- this article explains the possibilities (and this one explains YouTube's Content ID system). We do hope Viacom considered fair use before issuing the takedown -- here's why. As for fair use, here are the rules used by judges and summaries of some of the cases.