I've rented quite a few fitness DVD's from Netflix (they have some stinkers in there!). It's good to "try before you buy" to save some money!
Unless they've improved their listing system recently, though, fitness videos are sometimes hard to find. They don't all seem to be listed together (I had a hard time finding the Push/Pull Fitprime workout DvD and the other Kickbutt workout DVD that was released withh it--or maybe Push/Pull was Kickbutt and Fitprime was two other workouts?)
If you are a Netflix member, you can always request DVD's. If enough people request Cathe DVD's, they may add them to their selection.