i don't feel too much either... maybe they are just simple
From what I see, I think the pro version has more intense workouts for the advanced.
Thats funny. I find these the hardest ab workout. Are you leaning as far back as you can with feet off the ground? I also turn my head and shoulders (not just hands) from side to side which is harder.
For me russian twists do work very well. Try to lean more back or turn your whole upper body from side to side, not just hands. Its very much about the angle where your body is, but if you still wont feel the pain, try it with a weight!
David said what I was thinking. Make sure you lean back, feet up and twist from your shoulders & chest. You can add weights & make sure to twist slowly.