Not a bad price for this. I have and use a FoodSaver marinade box for years, which is similar but uses the FoodSaver pump and a hose to evacuate the air. The FoodSaver box is quite a bit more expensive @ ~$33.
Presumably it works as lowering the ambient pressure air is withdrawn from the meat – you can see the bubbles come out. This allows the marinade into the tissue better. Pumping and releasing the pressure a couple of times seems to work better for as the pressure is released, the marinade is forced into the tissue. I use it primarily when I have forgotten to marinate before hand.
It also works well to wet wood chips for a smoker, if you forgot to do that a day ahead. You can get the chips considerably wetter in a few minutes than with just a dunk.
The Jim Beam people should assign someone to clean up the English in the instruction diagram – especially the last part about the fact that the pressure will decrease a bit on chilling. I get what they are trying to say, but it is hilariously awkward. In any case, I doubt that the pressure decreases that much on going from ambient room temperature to refrigerator temperature of around 40°F or less.