[ewidar]

That would be whoever owns the private key, no?

It's similar to any other private/public key scheme: it just serves to prove the signature was generated by the owner (here whoever owns the location at which the video is taken).

But I guess you could imagine multiple flickering patterns per location, with each pattern being owned by a different entity (an NGO + a governement + a private company for example), in essence doing a multi-sig of the video.