I agree that it's bogus. When played in reverse the octopus actually springs little fronds that are akin to the plant that it's blending in to. If it weren't for that, it would possibly be up to question for me.
The mimic octopus is pretty cool too, I saw one on a David Attenborough programme on BBC1 last year. It can do a remarkable job of impersonating a sea snake, a flounder (flatfish), and a lion fish, and quite a few other things, apparently.