This seems to be an issue with the new DesktopVideo 10.x software/drivers.
If I uninstall and go back to 9.9.3 the 'Blackmagic' device shows up in VLC, and it shows up as an AVFoundation device in any software that uses that API.
With 10.x it doesn't show up. I think there was ONE time where it showed up in my custom software (which uses AVFoundation), but it never showed up again in any AVFoundation program that enumerated available capture devices.
Is there a bug tracker or some place I can report this? It would be great to have this fixed/resolved