In fact, Gracie Academy Torrance allows students who learn via the DVD to test for their "Combatives Belt" (a belt of rank just below blue belt) by submitting a video or visiting the academy. You don't need to sign a long-term gym contract to get your first taste of ranking. While the DVD alone cannot award you a belt (you need a live instructor to verify your technique for safety), it provides the map to get there.
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 core philosophy of the Gracie Combatives program is that a student need not master thousands of techniques to be effective in a street fight. Instead, the program distills the art down to the 36 techniques deemed most essential for real-world encounters.