Are there video "thumbprints" like exists for audio (used by soundhound/etc) - IE a compressed set of features that can reliably be linked in unique content? I would expect that is possible and a lot faster lookup for 2 frames a second. If this is the case, the "your device is taking a snapshot every 30 seconds" sounds a lot worse (not defending it - it's still something I hope can be legislated away - something can be bad and still exaggerated by media)