The National Geographic Channel is using humor to sell it's ambitious new special Stonehenge Decoded. Christopher Guest has resurrected his Spinal Tap alter ego for National Geographic Channel, lead guitarist Nigel Tufnel, to expound on his theories about how Stonehenge came to be. Naturally, even as he's promoting the special and National Geographic, his tongue is firmly planted in cheek as he disses the findings of the scientists and purports to be an expert on the subject.

Guest as Tufnel is interviewed by straight man -- comic actor -- Jim Piddock, leading to riotous takes by Nigel about dinosaurs, the secret language of potatoes, the pyramids and other weighty affairs. Here's one of the videos (after the jump), so you can see what I mean: