it's some sort of fuzzy hashing technique. you have to run through every frame of every video and compute a number that represents that frame. to make the mat

it's some sort of fuzzy hashing technique. you have to run through every frame of every video and compute a number that represents that frame. to make the match approximate you have to come up with a hash function that is resilient to small changes, either by throwing away information or by some other means. then you have to store this fingerprint of the frame. then every time someone submits a video you compute the fingerprints of the frames and check against the ones already in your database. Each check is constant time since it's a hash table. If any/enough frames match, label it as a copy!