All you need is the Homebrew Channel to add your Wii to the hundreds-long list of devices in your house that can play DVDs. Previous DVD hacks required a modded console, but now you can grab a .DOL file and install a DVD-capable version of mplayer without opening the hood. It should also play video files off of an SD card, although this is still experimental. We haven't tested yet, but if you do, let us know if it works. [Hackmii]
@CutePuppyz: I tried this last night, and it is slightly out of sync, but there's a workaround. Namely, start up MPlayer, start playing your DVD, press 1 to bring up the menu, go to Preferences | Audio, and play with the delay setting until everything syncs up (for me, the magic number when watching Black on Broadway was -200 ms).
Hopefully, the next version will auto-sync better.