Unless it is a short enough video you will need a HD-DVD burner to make an HD-DVD, ether way you will need a HD-DVD player to play a HD DVD. However you can make a standard definition from your HDV video by sending it through compressor (you are on a mac so I assume you use FCP, DVD SP & Compressor) When you build the DVD in DVD SP as long as you set it to 16×9 it will play wide screen on a widescreen TV.
A cheeper and easier way to show it in HD would be to get an Apple TV and convert your video for that, the Apple TV supports 720p