So far it seems to be basically a "subsidized by universities" model. The people giving these lectures are earning traditional salaries in traditional professorships, paid for by a mixture of tuition, research grants, and (for state schools) tax money. Of course, that doesn't explain whether it'll be viable long-term for the universities to keep subsidizing it. My guess is they're hoping to either: 1) use it as a loss-leader that pulls in more traditional, tuition-paying students; and/or 2) use it as a loss-leader that pulls in some kind of other revenue source, e.g. impressing people at companies who are in charge of grant programs; and/or 3) charge at some point.