Is there some kind of private/public key signing technique for videos, when the camera creating a video signs it with some key providing a signature that can be verified for authenticity ? so you would be able to at least verify that the video was created at certain date on a certain camera ?
You can sign the data, but it won't help. Basically, the ability to fake any video means that other data is needed to prove that the person/events in the video was in fact the person/events that that video is claimed to depict. Other proof, other measurements of the same events, etc. Deep fakes mean people will know they can't trust their eyes, they need to think critically. That's been true for a while, but now they…
But I guess this is wishful thinking given that we don't even generally sign written comments yet.