Unfortunately, they play up to the camera like kids do when they realize they are being filmed. They might as well have a hand written sign on cardboard in crayon held up before the vid stating this is their "show"...and sock puppets, F-it why not at this point.
But it's also natural audio. Someone had to go back and keep replaying Wave of Mutilation throughout this process. And the stupid bastards apparently forgot about the far more appropriate Pixies songs: Broken Face and Gouge Away.