It's not defense. It's attack. The reason that you use "double wrists control" is to put a "fishing hook" on your opponent's body. In grappling, you will love your opponent to move in toward you. You will hate your opponent to move back away from you. With that "fishing hook" been established, when your opponent moves back, he will pull your body along with him. Also when you pull your opponent into you, you can borrow the counter force to pull you into your opponent. this way, you can close the gape much faster than just by using your own footwork.
There are many situations when you try to enter:
1. You move in and attack your opponent by surprise.
2. You use kick, punch to set up your clinch. When you move in like this, your opponent will know your intention when you throw the initial kick.
3. When your opponent attacks you, you wrap his punching arm, or catch his kicking leg and then enter.
The "double wrists control" is trying to attack by surprise, you have to "hide your intention" as much as possible. Move in close without letting your opponent to detect it. You then suddenly jump in and attack.
In you clip at 0.10, she tries to break the grips by turning against her opponent's 4 fingers. If her opponent has strong grip, it's very difficult to do so. This is why to turn against the thumb (1 finger) is important. If you want your opponent to turn and break your grips in certain way, not want your opponent to turn and break your grips in the other way, you will hold your opponent's wrist in a certain way.