That's why they carefully speak of "theories" only.
It doesnt hurt to open its mind and hear and feel something different.
Like the nobel prize a few years ago who admitted he made his discovery about genetics and dna mutations after seeing and living it on a lsd trip.
Every explanation we have of the world around us is a "theory". Theory of gravity, theory of plate tectonics, theory of surface tension, theory of crystalline structures ect... The word theory used in pop culture makes it seem like there are many equally plausible explanations. Sometimes there are, but most of the time, when you read about any established modern scientific theory, it is the best explanation for a certain event or phenomena and has yet to be falsified. The ideas on Ancient Aliens, are not actually developed theories, they would be considered more or less a hypothesis.
It's true it doesn't hurt to keep an open mind, in fact, that's how many important discoveries have been made. However, you have to take in consideration when to keep an open mind. In a case like this, where History channel is providing a show for entertainment, and the fact that the "experts" in the show have no background in the stuff they speak about, it should not be taken seriously.
And yes, there have been many scientists that have discovered great things under the influence. However, the difference is, they already had a background in scientific studies, research, and experimentation to expound upon after lighting up. Where-as a normal Joe does not have as much knowledge as the experts in a certain area of study to allow for an enlightening idea in that field. Come back to me when a politician lights up and wins the Nobel Prize for the discovery of missing particles in quantum mechanics