If I understand trial law correctly, the rules of evidence already prohibit introducing a video at trial without proving where it came from (for example, testimony from a security guard that a given video came from a given security camera).
But social media has no rules of evidence. Already I see AI-generated images as illustrations on many conspiracy theory posts. People's resistance to believing images and videos from sketchy sources is going to have to increase very fast (especially for images and videos that they agree with).
All the more reason why we need to rely on the courts and not the mob justice (in the social sense) which has become popular over the last several years.
Nothing will change. Confirmation bias junkies already accept far worse fakes. People who use trusted sources will continue doing so. Bumping the quantity/quality of fabricated horseshit won't move the needle.
But social media has no rules of evidence. Already I see AI-generated images as illustrations on many conspiracy theory posts. People's resistance to believing images and videos from sketchy sources is going to have to increase very fast (especially for images and videos that they agree with).