David Blaine uses two methods to appear to levitate. He performs the Balducci levitation trick for his spectators and records their reaction. He records a separate scene with the aid of wires, but without an audience. The videos are edited together to make it seem like he has levitated.
The Balducci levitation trick is performed by standing a few feet from the audience and standing on the tiptoes of one foot (the one furthest from the audience's view) while the nearest foot is raised a few inches off the ground. This creates the illusion that both feet have been lifted off the ground.