Okay, this time the persistent translation of what should be "back side" as "backside" warped the story. Unless the guy is displaying the pictures across his butt.
He probably mounted an actual camera to the centre of the "costume lens" and hooked up a wireless shutter release to be pressed on his costume. Then, all it takes is a USB connection to the laptop on the back or whatever, and he's all set. Not that hard, but very creative.