Oh, and about the Dolbut ProLogic II request, I also wanted to add that this is the defacto professional way to create a soundtrack for a movie when only two channels can be stored; it is used everywhere from the optical analog soundtrack on actual theatre film copies through VHS stereo to additional language DVD soundtracks.

But DVDFab only creates a flat stereo downmix (as of 3.0.8.6).

If DVDFab's authors wanted to get really fancy they could also consider an option for creating Dolby Headphone surround downmixes which would be great for mobile devices. Clearly this is lower priority though.