As an interesting addendum to “video is way too fast for audio”, frame rate modulation is kind of the reverse. If you quantized all your CV signals at 29.97Hz (frame rate) then your audio would have zippering and sound bad. But when you do this with video, it looks smooth and fluid, and prevents any mid-frame glitches.
So: VCV Rack – really powerful for animation, motion, and some audio rate modulation! This could help you get a ton of utility out of your video rig. Save the hardware for the modules that process and generate the video signal.
Also: Check out Diver. It’s specifically meant as an “audio source to video oscillator” conversion tool, allowing you to make 2D video waveforms out of an audio source.