I am completely new to pilates, so I can only tell you about 2 videos (beginner) that I've tried.
One is the Denise Austin Matwork, which has 2-20min workouts on it. She gives very good instruction on both breathing and technique, so for an absolute beginner like myself, I found that helpful. The other is a 2 video set I just got, it's the Living Arts Beginner and Intermediate Pilates set with Ana Caban. The beginner workout gives good instruction, but a different breathing technique than the Denise Austin video (so now I have NO CLUE how to breathe during pilates!), but again, it's basic, gives instruction on the basic pilates moves and it is approximately 25min.
In the few short weeks since adding pilates, I can feel a strengthening in my abs and back that were not there before, so I am a "pilates believer."
Donna