Thanks for the suggestion Jon. I click on the crop effect name, and then I can drag each of the crop handles one at a time, to resize and move the region by each handle. He’s dragging the entire crop region as one unit, so its size/ratio is unchanging. So he’s dragging the fixed size crop window around the scene to reveal different aspects of the frame, such as a face or a gray card. so he’s grabbing and dragging the crop region around the window as a whole, rather then one point at a time.
Let me know if there’s something I’m missing in your reply!