WebCam Monitor will monitor and record from one camera at a time. If you would like to use multiple cameras at the same time, please evaluate Security Monitor Pro.

Security Monitor Pro can simultaneously monitor 3 cameras, with motion detection. Since you want to minimize bandwidth, you should set the program to take 1 or 2 pictures every time it detects motion and email you the photos. Emailing photos will use much less bandwidth than uploading recorded video.