Amashi-waza (body shift and switch) is a form of Go-no-sen (response after opponent’s attack).

Amashi-Waza 

In its basic form it uses stretching the distance in order to avoid the attack and switch in direction to execute counter attack. The longer the distance involved the easier for initiating side to adjust and continue the attack.

In our video example, Dave shows a high level of amashi by operating within reia couple of inches, yet even that small space creates some strategic opportunities for an alert attacker. The challenge is not to “fall” into your own attack, but to finish it in spite of losing the target, when the opponent starts shifting back and continue chasing them while remaining ready to adapt.