According to this Engadget story, those of you brave enough to stick unsolicited software on your Wii can now enjoy DVD playback. Read what the site says. It’s easier.
By installing a small, hidden channel on a system, this package blesses the console with a libdi file (DVD access library), and allows you to watch your favorite videos with the MPlayer application, an open source media player. The install file will run on modded and unmodded systems, and the software is also capable of playing media from SD cards (though it’s experimental right now).
Follow the link for how to do it.