A dead cat doesn't fluff up it's tail when its in danger - that that tail was definitely fluffed up. The stop motion effect makes it difficult to tell if the cat is moving or not, but you can tell by the stance of the cat that it's actively trying to regain its balance - a dead limp cat would not have its hind legs up and back, for instance, they would hang limply down.I sincerely doubt a live cat would have been so docile.