Very cool video...below is some info taken from Wikipedia.
"The sarcastic fringehead (Neoclinus blanchardi) is a ferocious fish which has a large mouth and aggressive territorial behaviour. When two fringeheads have a territorial battle, they wrestle by pressing their distended mouths against each other, as if they were kissing. This allows them to determine which is the larger fish, which establishes dominance. [1]"