June 16th, 2009 - The HD download is now working. The video in question *MUST* have the HD logo displayed at the bottom right of the video for it to work. If there is no HD logo, no HD video is available and, therefore, the download will kick out an error. Please be aware that the downloaded file will probably be huge. I've gone ahead and changed the example to one where the HD is available. It is over 24 megs in size.
June 14th, 2009 - Fixed yet again. Not sure how long it'll last this time around. The HD downloader is still having issues though and works on a case by case basis. You may want to try the normal youtube *.mp4 downloader.
This downloader will give you an *.mp4 High Definition file.