I agree that it's eminently tech-solvable. Experts can still analyze the pixels and determine if anything fishy happened. I think the societal problem is more if/when people make up their minds to not trust those experts when they call out a fake and just believe it anyway because they want to believe it.
An example would be, some fake video circulates of some politician saying or doing something they never said or did. Maybe someone created it to harm that politician, maybe it was a prank, doesn't matter. A day later, a gazillion experts do the analysis and come out with public evidence that the video was a fake. Great. Then someone like Alex Jones tells his millions of listeners that he knows better, and some world-class expert who he mysteriously won't name told him privately that the video was real, and that somehow all of those experts were in on a conspiracy to debunk it, even though the evidence they provided debunking the video is all out in public (if perhaps too technical for most people). And then, voila. Millions of people now decide that it was real after all, and that all of those scientists and engineers and law enforcement people who said it was fake are all in on some conspiracy to squash the truth.
So you're right, it is a tech-created problem, and presumably tech solutions will always exist, but as long as you have an uneducated segment of the population that will always just believe whatever their tribe tells them, those tech solutions won't even matter. I don't know how to solve that problem, other than people becoming more educated and less geographically isolated, so that they can recognize and trust expert analysis when it's available and trustworthy.
Put another way, the problem isn't that Alex Jones exists, but that there exist people who think he's credible. The very existence of his listeners is a much bigger problem than his own existence. There will always be conspiracy theorists and there will always be faked evidence to support them, but what holds society together is our collective ability to acknowledge well-documented bullshit as bullshit, regardless of what tribe someone thinks they belong to and regardless of what they want to believe.