The EPA has yet to approve any additive or device that "Increases mileage". In most cases mileage actually goes down. In the rare case that mileage goes up (slightly) emissions are compromised, or its just not economical (additive costs more than the gasoline it saves). A common mistake people make in evaluating fuel economy with additives, is to account for the volume of additive added. For example, if one quart of additive was added to 10 gallons of fuel, then you no longer have 10 gallons of fuel, you have 10.25 gallons of fuel.
We get people on this site daily trying to peddle stuff like this, and I have yet to see any of these actually work. The most effective thing you can do to increase your fuel economy is to modify your driving habits, and that's free.
A 5% improvement on normal operating is not worth the time or bother. The Video that is posted on YouTube for the product makes certain claims, but they are un-provable other than anecdotal, as the references are highly dubious.