The Electronic Frontier Foundation's Fred von Lohmann sez, "Hearings for the DMCA triennial rulemaking are going on this week in DC, where the educational community is asking for an exemption to rip DVDs to take clips for classroom use. The MPAA responded with a video showing how to camcord (!) movies from a flat screen monitor, arguing that educators and students should do this instead of ripping DVDs. In the words of media literacy researcher Martine Courant Rife, that's like typing up a quote from a book, taking it outside, chiseling the words in a rock, photographing the rock, scanning the photo, and running OCR on it. And for what?"
DVD movies are almost always copy guarded and I couldn't even copy any of them I tried when I had my GO player up and running (DVD/VHS combo). So unless one has separate components and wants to buy a bootlegged copy guard electronic decoder unit, you can't rip nearly any DVD's except those you make yourself. MacroVision is the common copy guard but you seldom see their logo pop up before or after a movie. Documentaries are less likely to be copy guarded, like a National Geographic special.