Like when you’re at the bank and a bank robber shoots a bunch of people and then you jump out from cover and start covering all the corpses eyes super fast.
So whatever way the camera output is being signed, what’s stopping you from signing an altered video with a similar private key and then saying “you can all trust that my video is real because I have the private key for it.”
The doubters will have to concede that the video did indeed come from you because it pairs with your key, but why would anyone trust that the key came from the camera step instead of coming from the editing step?
It all started when I was a young child and my mother took me to the big mall one town over. The one with the two story Sears that had the childs pants on the second floor.