Video capture is the process of taking video from an external hardware source, such as analog video, and digitizing it into a form that can be used on a computer. VirtualDub allows use of several classes of video capture hardware to do this conversion, depositing the result as an .avi file on disk.
In order to use VirtualDub's video capture mode, you need:
Video capture mode cannot be used to capture streaming video over a network or graphics on your own local machine (unless you loop-back TV out into a video capture device).