"Proof" for thousands of years was whatever was written down, and that was even easier to forge.
There was a brief time (maybe 100 years at the most) where photos and videos were practically proof of something happening; that is coming to an end now, but that's just a regression to the mean, not new territory.
Hmmm. Actually I think I finally figured out why I dislike this argument, so thank you.
The important number here isn't the total years something has been true, when talking about something with sociocultural momentum, like the expectation that a recording/video is truthful.
Instead, the important number seems to me to be the total number of lived human years where the thing has been true. In the case of reliable recordings, the last hundred years with billions of humans has a lot more cultural weight than the thousands of preceding years by virtue of there having been far more human years lived with than without the expectation.
That's a false metric. With exponential progress, we have to adjust equally rapidly. It's quite obvious that photos and videos would last far shorter than written medium as proof of something.
Photos have never been a fundamental proof if the stakes are high or you have an idling censorship institution. Soviets (and maybe others, I just happen to know only about them ) successfully edited photos and then mass-reproduced them.
There was a brief time (maybe 100 years at the most) where photos and videos were practically proof of something happening; that is coming to an end now, but that's just a regression to the mean, not new territory.