Motion Capture

Motion Capture is usually used to produce a more natural looking body animations and is now being increasingly used in games.
To hype up Naughty Dog's latest game, The Last of Us, they have released a behind the scenes of the games trailer featuring motion capture. The video demonstrates the processes the actors and the animators and the animation go through to create the final product.

Motion capture advantage is that it produces natural body motion that could not be achieved with just animating a model. You are able to capture the little details that make it look more realistic.
One great example being the gameplay trailer for Far Cry 3. Far Cry 3 features Vaas, the guy who gives the insanity speech. He is motion captured by Micheal Ando who gives the character a very unsettling, tense atmosphere. Far Cry 3 uses technology that records body and facial expressions simultaneously.
Through motion capture, actors can be used to really capture a character's mood, creating a good atmosphere and overall, an awesome game experience.