Exactly, so if I upload something and say "Look what I just recorded off the BBC!" you _shouldn't_ believe me if creating a deep-fake becomes as easy as recording the real thing.

In that scenario, you'd want people to say "but wait, there's no signature on this, it could be fake" and then only trust the video as much as you trust the source (not the claimed source).

Lack of the right kind of metadata would be the first tell.

While still maintaining a verifiable origin