looks like she would need to have a flat stomac already to 'see' any benefit... It doesn't look like it would burn much fat, ie, doesn't look like there is a cardio benefit and for 3 mins a day, there is deffinetly no cardio benefit. For 3 mins a day it is obviously a toning device.
Probably works (to tone), but these things always come with a manual which stresses a healthy low fat diet, and if the person using this is over wieght, that is where they will see most of the benefit, not from the contraption.
I would see this as something to tone and ad some strengh to your core muscles, which is good, but nothing more. You need to be doing more than this to get fit or lose weight.
They always make these things sound too good to be true, and then highlight the need for a combination of the right diet.
The only way to get fit and lose weight is to put the work in and change your lifestyle/eating habbits (not crash diets) - there is no easy way around it.