I'm surprised few people are actually discussing this, digital signatures seem like the right way to go for footage like security recordings or recordings that can serve as evidence that must be trusted.

Discussion below[0]

[0] https://news.ycombinator.com/item?id=17136292

This still depends on trust and tamper-proof devices. You don't need the keys if you can alter the input stream.

Indeed, but it ups the ante. It requires someone creating a spoof expend more work rather than just training a NN to fabricate a video.

I think everyone knows this, security just makes things harder, and that might be enough.