Just an update on my video switching situation. I was able to get the component video switcher working as expected by removing a few capacitors from the circuit on both the input and output channels. I'm using the digital audio line (modded) to carry the composite sync signal.
The switcher appears to boost the video signal, so I may end up not needing any other signal processing. Only one problem: One of the video channels appears to drop one entire color completely. I've checked for shorts and traced the issue to one of the ICs used to switch the signals.
I'm also working on the video overlay circuit... I still need to prototype the design, but I've got most of the circuit components I need.
What project would be complete without custom labels? :) The beautiful painting in the background comes from "Art by Bones". The label isn't the final version, but it shows a semi-standardized layout for different artwork elements.