As I understand it, this only works with still images that scroll vertically.

Each revolution is one frame, so if you compare the data paths next to each other, they don't make up an image but the same single line of several consecutive frames.

Scrolling a still image makes the same line on the screen cover a different part of the image each frame, so you can sort of make out what the original image looked like.

The end credits should show up as a single tall image, since the only limit to the height is the radius of the disc.