Wow still can't believe nobody read far down enough to see:
"How did we do it technically? Well, as you can see on the comments, 95% believed (and still believe) that it was all done in post production. However, all we really did was rent the screens and had our footage loop there for hours. The clips had visual sync points which allowed us to sync the iPhone version of the video. Once the sync was done, then it was a piece of cake from there. The actor was familiar with the timing of the "hacks". We did hundreds of takes on each screen."