There is no reason to think the video is anything but legitimate. The video was filmed in Dunsborough, Western Australia. This region is home to the Western Australian common octopus — closely related to the common Sydney octopus but recently determined to be its own species. This species, as seen in the video, is “commonly found in and around inshore reef systems and sandy benthos” and it “completes its life cycle in nearshore and continental shelf waters.” Speaking to The New York Times, Peter Ulric Tse, a professor of cognitive neuroscience at Dartmouth College who studies octopus cognition, said that octopuses, in general, “can express what we would call aggression when they feel threatened or when they feel their territory is under threat.” Tse said that the behavior captured in Karlson’s video is likely a warning not an attempted attack.