Finding an original copy on a go-pro would likely be pretty compelling evidence but this (and the more scary politically centered questions like this) are why I wish we had a way to build a durable chain of custody into these technologies. It is infeasible from everything I've seen but it would be a big win for society.
Do you? Consider for a moment all the dissidents and protestors who would be ensnared by their own devices then, with no "it was all ai" defense available?