When you record 16:9 video, its designed to play back on a 16:9 Television - which expands the "squished" video to fill the entire frame. If you wish to display your content on a 4:3 tv, you'll need to encode your video to anamorphic 16:9 DVD. DVD players will automatically detect the anamorphic flag and add letterboxing to the video.
www.philipwilliams.com
[EDIT]Dang this group is fast.. I'm still typing away and Boyd already posted![/EDIT]