Originally posted by another user
Start by balancing your phone upright on a flat surface (a granite countertop or glass table). The surface has to be really smooth, so don't expect any non-laminated wood or tiles to work.
Once you press "GO", the app will make the phone vibrate at just the right frequencies to force to phone into a twirl. Your iPhone will continue to spin in a circle, which recording video, until you press the "STOP" button.