What the basic idea behind the belt is that if you straighten your knees up you will feel tension in the cords, so basically you try to keep the cords slack the entire time. It gets you in the habit of getting down and in the "athletic position" and it gives you a good lower body workout while it does this.
"I got dosed by you and
Closer than most to you and
What am I supposed to do, take it away ."
-Red Hot Chili Peppers, Dosed