'The Social Network' Behind the Scenes Video: From Whence the Winklevoss

Flashy, eye-popping special effects (á la "Tron: Legacy") are always great, but the sign of a special effects job truly well done is when you can't even tell there's any CGI at all.

For instance, many viewers didn't even know that the Winklevoss twins in "The Social Network" were played by only one actor, Armie Hammer. Well, they were sort of played by one actor: another performer, Josh Pence, stood in as the other Winklevoss opposite Armie in any shot that had both twins in frame. Later, the decision was made to have the Winklevoss twins be identical, and Josh's face was replaced digitally by Armie's face. Thus, the Winklevii were born.

Is that fair to Josh Pence? Not really, in fact it kind of sucks. Pence was a tad upset when they told him the news: "I threw the phone through the wall, started throwing up, and crying," said Pence, half-joking. But he has no regrets about being in the movie, saying "I was happy to be a part of this regardless…you get over your ego and you realize that it's a no-brainer." He went on to say that the chance to work with Aaron Sorkin and David Fincher was reward enough for him.

The technology is certainly impressive, and might have only gotten better since facial replacement was used heavily in "The Curious Case of Benjamin Button". The fact that many moviegoers actually though that Armie Hammer had a twin brother is a testament to the level of detail used here.

Vulture has an exclusive extended video entitled "The Winklevii Genesis" detailing the process, and includes some behind-the-scenes looks at how they put Hammer's face on Pence's body. It includes medical laser scanners and a giant contraption that looks like a cross between something from "The Fly" and "Contact". Check it out below, and get ready to be wowed.