It's been 3 years, and I'm revisiting this project, hopefully to create a device that "normalizes" this "revolting video waveform" (well said ppppenguin!)
I'm going to start with a build of this guy's composite video adapter circuit:
https://youtu.be/5FYF5uhCzAM
Hopefully, I'll see if I can develop it into a "normalizer", but still have composite video output to use with my computer/USB capture devices. That way I can record nice clean signals from these very rare system terminals.
I welcome any input from the experts here!