Its not a scam. I sued vubraplate with a personal trainner for a while. It causes unbalance and that will make you use your muscles more.
I'm not talking about just stading in the vibraplate, but do squats, lunges with one leg on the of the vibraplate, push-ups with your hands on top of the vibraplte, abs even...
Its so different making push-ups vibra-plate.
BUT...I did this because the gym had a couple of machines. Is it worth buying one? NO WAY!