Sure, for a casual observer, these new methods for generating videos appear convincing, but is that the right bar to judge "ability to fake evidence"?
As far as I know, there have always been more sophisticated techniques and forensics to determine if an image is doctored, and likewise for video. I've not seen any research tackling fooling those methods yet, and I would bet that naive implementations of neural networks for generating videos would leave very obvious "neural network" artifacts. Of course, this is still new technology, so it will obviously get better at fooling our other tools over time too, but as of right now, I don't think the clamoring for "all evidence can now be faked" is all that justified.