The Bt878 WDM Video Capture driver is a Windows driver for devices that use the BT878 chip, which is commonly used in video capture cards. These cards are often used to capture video from analog sources, such as VHS tapes, TV signals, or other composite video inputs, and convert them into a digital format for your computer. The WDM (Windows Driver Model) indicates that this driver is designed to work with the Windows operating system, enabling the capture card to interface with video editing or capture software.