If you are able to connect your computer to a TV you can watch the videos from Demand Five. In most cases you can connect to a TV from your computer's video card using a VGA or an S-video cable. These are the standard connections for video on most modern televisions and computer video cards.
The VGA or S-video cable is only for the video picture so you will also need to connect the audio from your computer to your TV or your home stereo system. This is usually done using an RCA cable, which plugs in to your computer's audio or video card.
Please check the documentation that came with your computer for more information about its capability to link to a television or home stereo.
If your computer is a Microsoft Media Centre you can find more detailed information on the Microsoft website at:
http://www.microsoft.com/windowsxp/mediacenter/default.mspx