Can I ask: what the hell is Wii fit?
Wii is a video game system that hooks up to your TV.
It plays games like baseball, bowling, tennis, golf, etc. You secure the controller to your wrist, and stand in front of the TV. To play, you swing your arm as if you are throwing the bowling ball, or swing it like a tennis racquet or baseball bat, so you do get some activity playing.
Wii Fit is a disc you can put it to exercise with. It also comes with a platform that you stand on during the workouts.
Wii Fit will weigh you, calculate your BMI and track your weight loss. It has four groups of exercises. There is a Yoga section, a balance section, an aerobic section, and strength building section. The platform is sensitive to pressure, so when you balance, it tracks your movements and posture, and puts you through various exercises which will increase strength, flexibility, improve posture, tone muscles, and other things.
This bottom image shows what you are seeing on the tv....in the bottom right corner, is an image of the trainer exercising on your tv, and you mirror those movements using the platform.