This is what technology can do it for you. A hacker or geek (whatever) demonstrates how with iPhone, transmitter and repeater one can easily take over the control of what is displayed on the digital screen. He plugs in the transmitter into the headphone minjack of iPhone and then plays the any video and then this transmitter sends signal to repeater which is held close to the digital screen and you can see this video playing on the hacked screen. He chose times square only because there were a lot of screens to test on at this place. I wonder whether this hack works for other phone firmwares (symbians, blackberrys, android) also. Anyways it is open for anyone to try if that works.
I am also a bit in doubt of whether this is real or fake, but it is worth a try. Post in your comments about whether this works with other phones also or not.