That sounds promising. Because I'm not that technical with this sort of thing I didn't even know what to ask for! Just so happens I know someone who set up some donkey Kong cabs for live streaming. He might be able to point me in the right direction 🙂
But otherwise, I experimented with my mobile phone and a scanner at work. Even with that scanners screen size I was able to get a pretty good picture of just 1/6 of the scanners screen. So camera to LCD works ok. I'm guessing camera to CRT would be trickier because of the scan lines