> It used to be if you saw a video or a photo depicting an event you could be pretty sure that what you're looking at actually happened.

This isn't really true. Image manipulation was long possible in the darkroom,[0] and you only need to look to hollywood to see how extraordinary deception can be done. The only thing that's changed these days is cost and ease of doing such manipulations.

[0]: https://en.wikipedia.org/wiki/Censorship_of_images_in_the_So...