Well you should be able to use Snapz Pro X (
http://www.ambrosiasw.com/utilities/snapzprox/ ) successfully- in the FAQs about it they have this:
Q. "How can I capture images from DVD?
[How To...] submitted by MagnusApollo -- Aug 24 2005, 10:03 AM
#20
A.
Snapz Pro X 2 should have no problems capturing audio and video from a DVD, provided the machine it is installed on is capable of using Apple's Quartz Extreme for video display.
When Apple introduced OS X 10.2, they moved video display from the main processing unit to the graphics processing unit, provided the computer was capable. This enabled Snapz Pro X to see, and therefore, capture DVD display. The first generation G4s with PCI video cards are not capable of displaying QE, but most newer computers should have no problems doing so.
If you find you are unable to capture from DVD, you may have better luck using the Video Lan Client. It is an open source video player capable of displaying almost any video format on your Mac, including DVD.
Go to:
http://www.videolan.org/
Please note: Ambrosia Software, Inc. does not make nor support the Video Lan Client.
The best way to ensure Snapz Pro X 2 does exactly what you want on your machine is to take advantage of the full-featured, free trial period."