"Motion Capture" files.. You know.. like the guy/girl with all the ping-pong balls on them moving around while a computer records all of their movement... Blender can import them and apply them to rigs (Some how / some way). Never done it myself... yet. (Forgive all of my technical terms... lol) :)

Reddog9
Tutorials, Samples and Models
www.blender3dclub.com