* You could "rip" it, then with software crop or edit out the portion you want.
** You could also use a capture card installed in the computer. One cheaper way to do this is with a DAZZLE or equiv... these are hardware devices that go between your DVD player and computer usually connected via USB for simplicity so you dont need to open the computer. CompUSA and the like have them. You can choose to record only the portion you want or get the whole thing and edit later (almost all of these come with basic software).
*** Send the DVD to a buddy or use a local conversion service to do it for you.
**** Finally, you can see if someone else already has this in a file format. Rather than point you closer to adware, porn, and browser hijackers I'll just say it might already be done and on the internet. This assumes you are working with something commercially made.