A mystery solved?

In my time, I have heard many explanations as to how the great stone circles such as Stonehenge were built. They have include using sound, levitation, mana, snow, etc. I have always tried to use Occam's Razor and look for the simplest explanation for any phenomenon. Sometimes, that simplest explanation can indeed be what we call magic. More often, however, it is not. I received this video on my Facebook page and it strikes me as utterly credible that very simple, mechanical, methods identical or similar to these may have been used by our ancestors.