If you fall or are knocked down, you end up in the "Guard" position (on your back with your opponent between your legs). The DVDs teach the "Survival Posture" to prevent strikes and fundamental sweeps like the "Scissor Sweep" and "Pendulum Sweep" to reverse your position so you can get on top.
The Gracie Combatives DVD offers several benefits, including:
Positional Control, Headlock Escapes, and Shrimp Escape.