Bump the hip forward and back, not just forward
The hip bump is not just a forward move; it is forward and back, taking the belt buckle back at about a 45-degree angle. The coach says it feels like the femur getting on top of the lead (left) leg, creating a post, and it keeps the hips square. Setting the pelvis this way, with the sternum kept still, lets you turn behind the ball with ease without straining the lower back.
Channel: PorzakGolf
Watch official source at 0:17Why this context matters
Central concept of the video, restated several times for viewers.