I'm pretty sure that's doable with current technology. Detecting a QR code and a larger rectangle surrounding it is easy; overlaying a video over that rectangle

I'm pretty sure that's doable with current technology. Detecting a QR code and a larger rectangle surrounding it is easy; overlaying a video over that rectangle is only slightly harder. What I'm not so sure of is the utility. Users would probably rather watch a video on their phone screen than watching a video pretending to be on a piece of paper through their phone screen.