"Get out of here you guys! You don't want no part in this!"

Less to scare them away (aggressive) as to appear distasteful or dangerous to eat (defensive).

^Good point.

Anyone care to name all the shapes it goes through? There's a stingray at around 1:40, and a turtle at the end.

I see a sort-of scorpion around 1:48

It looks like a lot of it motions are trying to find a cavity to crawl into. Actually, it looks like it's foraging, many of the movements in the first half of the video are it turning over a small piece of coral rubble, but it's hard to imagine it's thinking about food when surrounded by 3 divers.

^and notarobot,funny that you see a scorpion. I was just thinking that the "stingray" looks more like the flying gunard, which is common to some of the areas in Indonesia where the mimic is found. It's in the order Scorpaeniformes, as are lionfish which mimics supposedly mimic. I'm guessing the order was so named because of the poisonous spines of the fish rather than any general resemblance.

I see tits.