I haven't seen the video yet, but I've heard about an octopus in aquarium somewhere. They've decided to put this octopus inside the shark tank, but were afraid the sharks might attack the octopus. Later, they've discovered sharks started missing!
Edit:
Holy cow! I think the video is of that aquarium.
they show these "animal wars" on discovery pretty cool. I saw a hippo vs a tiger shark. Hippo bit the thing to death. It's like fighting a 300 lb man in McDonalds for a place in line.