Hi

As long as you can use just one of the outputs you can do as we did:
Use the S-Video (Y/C) output on the GraphicsCard.

S-Video - Adaptor MiniDin to Coax - S-Video to SDI Interface AJA D5D.

(You might have to start the G5 with a 75Ohm conected to the output, otherwise the G5 doesnt start the Y/C out.)

Works well for simpler purposes.

All the best

Abbe Westerlundh