Belly rolling and pilates are really useful for shaping, but reducing belly is not shaping, but reducing body fat (abdominal muscles or vest line are shaping). The best way to reduce body fat is always aerobic exercise, so I suggest you run or swim for at least half an hour before doing this special training.
In fact, the most important thing is diet. If you eat chocolate dessert drinks all day, you might as well wash and sleep. . .
postscript
Now the traditional sit-ups have been basically eliminated. . .