The idea of "ancient aliens" isn't exactly new. It's been around for at least a century, if not more and to date, as far as I can tell there hasn't been a shred of solid evidence to back it up. Is it possible pre-historic humans at some point in the past encountered intelligent non-terrestrial life forms? Sure, but that's a far cry from proving it ever actually happened.
As for the show itself, I did what a lot of it, not because I buy into the idea so much as I find some of the real archaeological cases interesting...plus I have to admit I tend to think that all the supposed accounts of advanced technology witnessed my ancient peoples is more likely to point towards a lost chapter in human history. Also no an original idea I know *cough*Atlantis*cough* and again, it's not proof, but I think it's inherently more likely than "aliens did it."
What really bugs me though is what did that bloke to to make his hair dresser hate him so much?