Web cams are usually accessed through a library or the operating system rather than as low level USB devices. In python, one option to read webcam frame is https://github.com/gebart/python-v4l2capture or use my cross platform fork (including windows): https://github.com/TimSC/libvideolive
If you want to create a video stream that is accessible to other computers, you either need to emulate a webcam or an IP camera. A webcam can be emulated on windows by creating a custom media source. https://msdn.microsoft.com/en-us/library/windows/desktop/ms700134%28v=vs.85%29.aspx On linux, you need to stream data to v4l2loopback https://github.com/umlaeute/v4l2loopback. To emulate an IP camera, a good starting point is to base it on the tools available at http://live555.com/
