After spending some time going over the DBP CAP plugin, you are fighting an uphill battle that isn't going to come together before your deadline.
At best you might be able to have the user click on a button to grab an image of them self from the camera and send that as a static display, but live video wont be possible with the DBP CAP plugin, at least not at the quality and framerate you probably want.
I'm not saying it isn't possible, but it's certainly not ideal.
The only way I can think of to do it is to use DBP CAP to save individual frames, then load them back in to a MEMBLOCK, send that using DarkNet, make an image from it on the other side and paste it in the window. The resulting framerate would not be good at all, and there would be a significant delay.
Audio on the other hand isn't a problem, as DarkNet has that built in, although I've not used those commands yet.
Unless someone can write a different plugin for DBPro that gives you access to grab an image from the camera and store it in memory, that's the best I've got.
I could probably do it in C#.Net, and it sounds like a fun project, but I don't have the time to spare to research it and start another project. Sorry.
I'll stick with my original recommendation, your best bet is to do it in C#.Net. It will give you access to everything that Windows has to offer, and it's probably even got a system module to give you direct access to the camera data. (probably through TWAIN or something..)