The hack video will simply keep its correct dimensions and the rest of the hacked space will stay black. The video repeater overrides any video screen that it’s being held next to. Hackers: “i chose times square for my demo because it has lots of video screens to try it on. It is also one of the most monitored and secured areas in new york city and that made it that much more fun :). i will post a new video later this week explaining how i made this prototype.”
Source: https://thehackernews.com/2011/03/times-square-screens-hacked-using.html