When I print to tape my final rendered .avi file (which looks great on Windows Media Player) to my DV tape I lose part of the frame on the left and right side of the picture. If I then copy that final film over to VHS (I know, old school), I lose even more.
Televisions don't show all of the frame; some of it is hidden outside the edges of the visible screen. What is visible is known as the "safe area". This is done because picture tubes tend to have the image shrink as they age and the manufacturers all decided it was better to have an old television still fill the visible frame and not show empty space around the edge. Of course, this area varies as the television ages, and even varies from one television set to another. All commercial/professional television production takes this into account and makes sure the edges of the image are filled with unnecessary "stuff".
How are you viewing your DV tape? If you're using the LCD panel of your camcorder, this probably also hides some of the edges to help you when shooting your video to keep it within the safe area. Your television just happens to cut off more than the LCD panel does. Media Player, on the other hand, shows you the entire frame.
Vegas has a nifty "safe areas" overlay for the preview window that lets you see, approximately, what will probably show up on a television screen. For VideoFactory, you can download one of these files:
Place the appropriate file in the video overlay track wherever you want to check the safe areas. A pair of yellow dashed rectangles will appear in the preview window. Anything inside the inner rectangle will most likely be shown on any television screen. Anything outside the outer rectangle will most likely be hidden. Of course, you should remove this image from the overlay track before rendering.