QuickTime 3 Reference
QuickTime video output, which most often comes from QuickTime movies, can be displayed in windows that appear on a computer's desktop. Because these windows are created and managed by the computer's operating system, software that presents QuickTime video can use the operating system's video display services to specify which display (when there is more than one video display) and window to use for video output.
There are, however, many video output devices that are not recognized by operating systems. To display QuickTime video on these devices, your software can use video output components. The components, which are normally developed by the manufacturers of video output devices, provide a standard interface for video output to a device.