Sorry, it’s not that kind of cat fight.  These are actual cats going at it.  What’s so funny about this video is that there are two birds also getting in on the action here, and it kind of results in a weird 3 on 1 where one cat has to take on a cat and two birds.  When the birds aren’t actively trying to tip the scales, they can be seen standing around as if saying “Yeah!  Kick his ass!  Get him!”  Good stuff.