Thank Highmac!
I didn't post the link at the time, and won't now, but there was another video I found in a similar place about an Italian gameshow or something where the shovel of a diesel back-hoe was used to undress a model (if you look it up she never is more undressed than she would have been in a one piece bathing suit). That was what I would've asked "why" about but the answer was probably that the audience had a lot of Italian men in it!
I think Stonehenge was obviously about social and religious issues so the why goes deep into the culture of that time. I think the fact that it still exists and is a icon in our time is reason enough for a guy named Wally to try and duplicate it using something like the technology that the original was built with. As obsessions go I think it beats car racing or stripping a young lady with a back-hoe all to heck!