In that second video in the article, he's holding a cutout of the number 9. I wonder if he put it on the paper and traced the outline, including the inner circles, what he'd see. Would the lines be accurate until the pen strokes connected to make an '8' and the result would suddenly scramble?

Also, is it the shape itself or the fact that the shape is a number? In other words, if you put a random cutout of the number 8 on a tree branch rather than have him look at a sequence of numbers, would that make any difference?