Head movement on downswing

Tom as I review your indoor training videos I have a question about the downswing instruction. As I watch the right side bend movement which goes along with the hip pump the head appears to move down quite a lot with this movement. The head then moves up with the extension through the ball. As one watches our swing on video and place a circle around the head should the head remain steady within the circle or is there an up and down movement that is acceptable.