The octopus is a predator but normally only going "down" the food chain or defensive when threatened. Seem this one as evolved or is showing new behavior previously undocumented. it may well have been hunting behavior since it was aggressive and went after bird and man! There have been reports of them pulling divers masks and mouth pieces off when they are screwed with. The "ink squirt" is purely defensive and an aid to escape, notable not present in this vid or reports where gear was pulled from divers. That would imply they are not in full defensive mode while acting that way. Interesting.