I guarantee this works poorly, at best.

If this actually works solidly, Google is in deep, deep, deep shit. It would mean that I can put a mark on my non-AI videos and demand that Google not allow upload of my identifiably copyrighted content.

This would completely obliterate YouTube.

No, it wouldn't. ContentID is already used by Google for that exact purpose. They appear to be fully in favor of enforcing IP law provided the owning party raises a complaint.