I'm a programmer and I'm interested in programmatic character animation — walking or running, bipedal or many-legged: what is the state of the art today?
IK Rig looks very cool, and from what I can find, it's all in the name. It's about using Inverse Kinematics, prescribing the bare minimum number of elements for describing an animation -- feet, pelvis, wrists, shoulders, neck-base and head. Everything in between is constrained according to artistic factors and calculated in-engine, or baked to a new, more fully-defined animation.
Based on slides downloaded from the description of one of their videos (see description, but be warned: 1.2 GB and not much information):
IK Rig Definition
● Active bones – full body IK
● Twist bones, small bones, secondary bones, collider, pivot, prop nodes – added and constrained directly in engine
This is accompanied by a picture of their IK rig's active bones -- feet, pelvis, wrists, shoulders, neck-base and head.
Another of their videos contains a more informative set of slides in its description (0.8 GB). It describes 3 steps:
Convert Source -- Mocap or other animation is converted into "IK chain proxy format".
Adjust -- Behaviours are changed/constrained according to the desires of the artist applying these animations to the character.
Apply to target -- These are then animated at runtime or saved as a more traditional animation.
With all this info, if I were you, I'd learn about Inverse Kinematics -- I've never done it before, but I'd probably Google "Inverse Kinematics" for more information on that specifically.