The DVDX installer will install a small, hidden, channel on your Wii that allows you to read DVDs on an unmodified system. It is not an installer for a patched IOS. You may however need one, depending on your system.
Usage of this package is fairly simple. Run the installer.dol found in the package, follow the onscreen instructions, and you’re done.
Once you’ve done that, you can enjoy the splendor of mplayer. That what started out as a simple proof of concept has rapidly turned into a full-featured media player, under the nourishing hands of dhewg. The main aim of the mplayer project was to get DVDVideo going, but it also supports reading video files off the SD card. (Experimental).
A patch for Wii64, the N64 emulator for the Wii, will also be available shortly. This patch will allow you to read games off a DVD.
If you have a modchip, you also need patchmii, in addition to the DVDX stub installer.