They do show it. 2:00 is the best view, but also at 1:31 and 1:53, plus several other times.

2:00, the hand rests on the ipad, draws, lifts, moves the image, rests on the screen again, then touches the pencil and begins drawing.

Check the 2:00 mark, plus several other times (1:31, 1:53, etc.). They’re resting their hands on it as they draw in several spots in the video.