Having finished the last post with a short discussion of hunting/foraging behavior in the octopus, I figured I should do a lighter post with some fun video examples of cephalopod predatory behavior.
This is a short video of an octopus hunting (I don't know the species) by For the Sea Productions. The octopus catches a fish, apparently by spreading its web and feeling around. There's some great color-changing behavior here, too. It's hard to know how typical this behavior is, though, as it's obviously influenced by the presence of the person filming.
This is a clip from Deep Sea 3D (I think - I haven't seen the IMAX film, but that's what the caption says) showing a visually-provoked attack on a crab. I believe that the octopus here is a Pacific giant octopus.
Let's not leave out the other cephalopods! In contrast to octopuses, cuttlefish are primarily visual predators, who shoot out two long tentacles (these are tentacles proper - they are distinct from arms, which octopuses also have) to grab their prey.
This video was made by the California Academy of Sciences, and shows some adorable cuttlefish attacking crabs. I'm not sure what species they are. Again, you can see dramatic color changes as the animals become aroused.
This one, also by the CAS, shows a great slow-motion shot of the cuttlefish tentacular strike.
I'll end with one of my favorite videos of cephalopod predation:
Notice how the octopus turns mostly white and spreads its arms when the cuttlefish (most likely Sepia apama, although I'm not sure) approaches. This is called the deimatic display, and it's a defensive behavior seen in adult octopuses.
I feel obligated to warn anyone reading this that when you search "octopus eating" or similar strings on youtube, you are much more likely to find videos of people eating octopuses than octopuses eating anything. : (