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.
And it just so happens in this video that the scrolling was at a speed where everything was preserved and also not stretched. Too slow and it would be elongated vertically on the disc and too fast and it would be compressed and you'd miss information.
LaserDiscs are not quite a digital medium. The video is an FM analog signal (composite). Digital PCM audio was introduced about half a decade into the format's life.
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.