He says to place soda in the freezer for three hours and 15 minutes—the point at which the liquid is colder than freezing, but not actually frozen yet. When you open the bottle to release the pressure, and then turn it upside down, the soda turns into a slushy—at least in theory.
You could gently open the bottle, releasing pressure slowly, and pour the soda into a container, causing it to freeze into slush while you pour. Pour the drink over an ice cube to get it to freeze. Another option is to slowly pour the soda into a clean cup, keeping it liquified.
You put a plastic bottle of soda pop or water in the freezer for a few minutes to get it ice cold. It's still a liquid when you take it out to enjoy but the second you twist the cap, the liquid instantly turns to slush!