Update: His name is Marc DeVidts and more info about his costume can be found at his site.
The coolest technical “costume” I saw at Dragon*Con was a guy with a hundred or so individually addressable RGB LEDs under a white outfit. He had them under wifi control from his cell phone. He could select colors, speed, intensity and many different patterns of flashing. The video shows a “random” effect, but I also saw things such as a “line” moving up and down that made it obvious that each cluster was individually addressable. Unless he was supposed to be the guy from Quantum Leap, I think it was just a cool technical effect and not a specific costume. Download Video