HDTV video capture refers to the process of recording or capturing high-definition video and audio from an HDTV source, such as a game console, camera, or another computer, and converting it into a digital format that can be stored, edited, or streamed. This usually involves using a video capture card or device to grab the video signal and then transmit it to a computer, where it can be recorded, processed, or streamed using software like OBS.