The connector is just a power connector for the Apple QuickTime Conferencing Cam 100 -- The cam plugs into "Svideo" to get a minimal amount of 12v power, and into the composite input port on the Mac.
Hypothetically the port may have worked at some point in the future, but would probably have needed an adapter to actually get any video from the QTC100 cam anyway, and then would have required that people in the '90s actually liked the AudioVision.
I personally love it, but kind of wish I had an 8100 to hook up to it, as it seems like that's the only time it would actually be a big help -- if you were using it with the onboard video on a machine that sat on the floor.
If they'd figured a way to reduce the cable more, I bet it would've been accepted more widely as a good idea. Although Apple has a history of introducing a cool new cable or connection method, and it being really really disapproved of by the users and the industry. For me, I say "go for it!" -- but that's mainly as someone who likes collecting those older systems. I really would like to grab one of those CRT ADC Studio Displays and a matching PowerMac G4, for example. I think it's a beautiful thing to be able to reduce cable clutter in a tower system, and the display isn't too shabby either.
[Insert Cool Signature here!]