It's supposed to carb it faster but hooking it up to 30 psi on the gas post for 2 or 3 days carbs it up quick enough. So to me, it sounds like screwing around with something to speed up a process that already happens pretty quick.
That being said, the only time I do actually carb through the out tube is for hop water because it seems like trying to carb from the gas post just will not happen, or takes way longer than I'd like to wait. So I will usually turn up the gas to 30 psi, put it on the outpost until bubbling slows down and then purge the headspace. I'll repeat this about 5 times and it seems to give it a good head start with carbonation.