This guy puts a couple gadgets on his iPhone, grabs a balloon, and BAM! He's famous.
This is his simple explanation:
he way it works is pretty simple: plug in my transmitter into the iphone 4 and play back any video clip. you can play it through the ipod feature or through the camera roll. the transmitter instantly sends the video signal to the video repeater and the video repeater overrides any video screen that it's being held next to. it doesn't matter what shape or size the hacked screen is because the hack video will simply keep its correct dimensions and the rest of the hacked space will stay black.
I mean, I don't know where I can get all those repeaters and transmitters and stuff, and I may need a smartphone for this, but once I figure it out- NYC HERE I COME. Watch out!