5 or 6 years ago I was using a B&W G3 with a USB 2.0 card and anElgato EyeTV 250. I think I was using 10.4

I don't think you could use OS9 for USB video capture because OS9 doesn't support USB 2.0 and USB 1.0 is way too slow.

However I recall that Elgato produced a firewire model at one time. Don't know if it had OS9 software or how hard it'd be to find