If I remember correctly, when person A signs up, and if person A directly gets 8 people (the number probibly varys) to sign up, person A gets a free [insert item here]. Each of those people that he gets to sign up have to find 8 new people.
When you sign up, it can be a number of things, ie, they can spam you, or as he is saying its a trial of something.
Regardless, you still get something for (almost) nothing.
Too bad its only in the USA.