This would I think be the ideal if it's possible. I'd love videos to have signatures that prove when it was recorded, that it was recorded from so and so a phone, that it hasn't had any modification, and maybe even optionally the GPS location (for like news organisations, to even more reliabily prove the validity of their media). And then have a way to have a video format that can allow certain modifications (eg colour grading), but encode that some aesthetic changes were made. And, more importantly, a way to denote that a region of video is a clip of a another video, and provide a backing signature for the validity of the clip.

That would allow a much strong verifiability of media. But I'm not sure if that would be possible...