I hadn't heard about TED.com until recently, but they have a number of fascinating videos on a whole host of subjects. All the ones I've seen have been worth watching, but this video with David Gallo describing the variety and behaviors of different sea animals has to be seen to be believed.
I also highly recommend this video of Joshua Klein talking about the intelligence of crows. Some of the footage is pretty amazing. In one clip, a crow fashions a hook out of a small piece of wire and uses it to retrieve a bit of food.