It should be possible to import that imformation by replacing the data in the movie release field with the dvd release info. Some provisos: It would of course have to bew out on dvd. IMDB doesn't always have a different date for the dvd release date. and perhaps the biggest hurdle of all is being able to modify the script to collect the information for IMDB.
My question isn't strictly related to IMDB because I was thinkin' to those websites dedicated to DVD's that offer a lot of informations about their merchandise. Some of these informations are already among the voices in XMM database and one of them is the release of the DVD (very useful to determine which edition is...).
Other infos useful for DVD collectors that can be found on websites are the language of the subtitles, number of DVDs in package and DVD type. These infos don't even find any specific place in XMM database but someone could use customs to import them, or I think so.