Long before Fatboy Slim was the electronica icon who wrote that song in the Nike commercial, he was resident D.J. at Brighton, England’s Big Beat Boutique, where he mixed rap, rock, and electronic music with all the subtlety of early Aerosmith. Which is a good thing. As if to show that the scattered, whatever-makes-them-dance aesthetic of “Praise You” has roots on the dance floor as well as in the ad agency, he’s released the long-imported On the Floor at the Boutique Mixed by Fatboy Slim (Astralwerks). Veering between dance-floor classics, hyperactive hip-hop remixes, and his own tunes, Fatboy Slim sounds less like a clever sampler than a deft D.J. willing to throw on anything to keep people moving. Which is a good thing.