the student body. That means the basic registration fees, which are not nominal these days, even at public schools. What you (usually) avoid paying are the $$$-per-credit-hour fees. Note also that, as implied by the name, you shouldn't expect access to the professor. (You can hear him, but not talk/question back. And you don't get your assignments graded or commented upon.) Same with this MIT thing, EXCEPT there are no fees at all. And a hands-on course (science, musical instrument, culinary) may not be worth the time at all.
Still, I see many good things in this.