I just had to Google that after reading this comment and WOW, this concept blows my mind. Of course, my first thought was "How in the hell does that even work"

I just had to Google that after reading this comment and WOW, this concept blows my mind. Of course, my first thought was "How in the hell does that even work" but it turns out there are identifying symbols in the paper so I guess they just have to store a mapping of PAPER POSITION -> TIME INDEX to make it work. Still a brilliant idea and execution.