My guess is a video card too. Maybe a framegrabber or genlock type device. I'm guessing the top "black cube" at the connector end above the RCA jack is an S-Video connector. The RCA jack would be your genlocked or time base corrected composite video.
The two DB-9 connectors would be the passthrough for the Amiga's RGB video, I'm guessing (although you would need that silver adaptor that Commodore made on your RGB port if you were using this thing on anything but A2000 with a flickerfixer or an A3000).
