Could you explain how feedforward is used in walking?
A good example is driving a car around a curve.

In a pure feedback system, you go straight until the error signal tells you that you're not in the center of the lane anymore, then adjust the steering to compensate.

Humans look ahead and see that a curve is coming up, and actually turn the wheel a little before entering the curve.  This pre-compensates for the lag in the car responding.

The other examples you cite are too complex to be useful in illustrating just the feed-forward part of the behavior.  There is a lot more to riding a skateboard, for example, than a simple control loop with feed-forward.