Its possible but, someone would have to write their own program and make a channel that could do it.
It is also possible that someone can modify the disc channel to launch an app if it detects a DVD video, but a lot less likely.
There is already a WiiMC channel, so DVD video is just 3 clicks away. (Channel, Start, Disc tab on WiiMC) So there just isnt any interest since it is already close enough.