>>33 I suppose the later part would require a deeper understanding of video perception; Further, I wouldn't sign a video I made unless I fully understood what perversions (distortions, errors,,) are signed; maybe there's some way to specify ``levels'' of signature, where I sign a video, and specify a class of perversions that are negligible (level 0), and further distortions, while still mostly preserving it, thus being suitable for being recognized as it, have a sufficiently low-fidelity to the original that the author would not want it to be considered as the artproduct that he signed.