I'm not aware of digitizer for NG Amiga is there any? You maybe mean plugin the Vidi digitizer to an NG Amiga? It is a parallel device.
Kamelito
You can use a TV card as a frame grabber. Elbox made a VHI driver which allowed you to use VHI Studio to grab images from compatible TV cards.
It's a shame their isn't an equivalent API available now.