The way he explains it, it sounds simple -- merely add an LED emitter and a receiver to the space where the strum bar usually goes, and then wire the controller up so that it registers a strum whenever the light beam is broken. Anyone can do that, right? The result is a guitar that strums when you wave your hand through the strum bar area. See the video after the break and marvel at the less-clicky, vaguely magical guitar!
[Thanks, Comet!]