I second the DVDDecryptor > BeSweet conversion. I've done it before using the Dave Matthews Band Listener Supported DVD. Even with a GUI for BeSweet, it's pretty complex. I think I needed two or three tries before I got it to work. (In the end, the sound was still kinda low, but I think I could have fixed that in the conversion process).
The
forums at DVDDecryptor are a pretty good starting place, as are the guides at
Doom9.net.
I wish I had a good step-by-step guide for you, but I didn't have enough foresight to actually document the process as I did it.