I've never been too impressed with the job of an "actor." I guess I've always thought that most people are capable of acting (pretending), they've just never tried it. I just ran across Benedict Cumberbatch's motion capture performance for the Hobbit and I have to say I was impressed.
In the video above you can see Cumberbatch's incredible performance which required him to crawl around the floor with a body suit, facial markers, and head mounted camera. For those of you (like me) who never actually saw the Hobbit, you can watch a quick clip about the creation of the dragon itself using the MoCap footage.
Of course the king of MoCap is Andy Serkis who played Gollum in Lord Of The Rings. In the video below you can see how the original Gollum was created and then how they made the computer generated character even better for the Hobbit films.