There a couple caveats. Box sets cost more. For example “Planet Earth: The Complete BBC Series” costs $9.95, and “The Ultimate Matrix Collection” costs $14.95. There is also a limit to one HD DVD title per household.
Here’s how it works. Just select from a list of Warner Bros. HD DVDs (up to 25), make the online purchase, send in your HD DVD cover art, and wait receive the Blu-ray Disc versions the movies within 4-5 weeks.
Here’s a link to the website.