Which DVD do you have? I have one of the 10 Minute Solution Pilates DVDs and I can do almost everything in the video (pushups are still not happenin' for me). I am 50 years old and started pilates at 182 lbs.
You might want to try exercisetv.tv to preview some workouts and/or go to Collage video - they have previews of most of the videos.
You can also to a search here on 3FC - several people have posted comments about pilates workouts that they have tried