For a great demo of an analog video graphics processor looking at itself, and a deep explanation of the chaos theory behind video feedback, to some cool mesmerizing boop boopity boop electronic music, check out Jim Crutchfield's video, "Space-Time Dynamics in Video Feedback":
"Self-Organization and Pattern Formation in an Image Processing System"
"A video camera views its monitor: information flows in a closed optical-electronic loop"
Here is his paper about it that he published in Physica (1984):
SPACE-TIME DYNAMICS IN VIDEO FEEDBACK
James P. Crutchfield
Center for Nonlinear Studies, Los Alamos National Laboratories, Los Alamos, New Mexico 87545, USA
Video feedback provides a readily available experimental system to study complex spatial and temporal dynamics. This article outlines the use and modeling of video feedback systems. It includes a discussion of video physics and proposes two models for video feedback dynamics based on a discrete-time iterated functional equation and on a reaction-diffusion partial differential equation. Color photographs illustrate results from actual video experiments. Digital computer simulations of the models reproduce the basic spatio-temporal dynamics found in the experiments.
A great youtube comment on the video:
Crutchfield's paper is massively influential for video artists. I've done very similar things to this. The key is to have an image processing system in the feedback loop. In this case, he's using a Sandin IP (you can see it at 1:05), which is an early video synthesizer (that you had to build yourself. there weren't even kits. Just a manual). That's where the colors are coming from, and I would guess the black and white fields that are obscuring parts of the image at points. I would bet he's using a black and white camera, too. To pull of video feedback like this successfully, you need to have control over all aspects of the video signal and you need a camera that allows you to manually control the iris and focus. That said, it's amazing and a lot of fun. And LZX industries makes something similar to the Sandin IP today.