To get the "with distinction mark" you need to score 85% or better in the course. It seems like the only gradeable items in this course are the quizzes, which I assume at this point are multiple choice.  The caveat here is that you can only take a quiz twice (and not the same quiz) to have it count for credit.

There are exercises in the course, but they are ungraded, so I am wondering how that works for non-self-motivated autodidacts.   While pondering this, I also came across and readthis article on the Chronicle on the Uneven Value of Academic Credit. What happens when Duke students take Duke MOOCs from Duke Professors and ask for those credits to count toward their degree?

This is not a hypothetical at this point, it is something that will happen sooner or later. And as our own universities start offering massive online courses,either as xMOOCs through edX or Coursera, or as cMOOCs through free online tools, the question will invariably come up.

Even if you take the MOOC out of the equation, it's still an interesting question to ask! For instance, prior to arriving to my current role, the department offered an online, 3 week, graduate course in January (in-between semesters). Our normal course offerings are 13 week courses in Fall, Spring and Summer.  On rare occasions we also had 6 week summer courses online.  If a student has the opportunity to knock out 3 graduate credits in 3 weeks, why belabor the whole affair and take that course in spring or fall when it's 13 weeks? I know that students have told me that they love those courses, but are those courses right for students? Are we doing them a disservice for offering those courses†? And, at the end of the day, are the 3 credits I earn in 3 weeks the same as the 3 credits that I busted my behind to earn in that super-hard-course that was 13 weeks, but really should have been 15?

Along with defining "academic rigor" we need to do a better job of what is deserving of 1 credit, 2 credits, or 3 credits. Butts-in-seats is not the underlying measure (or at least it shouldn't be), but I do believe that time spent in a class does have a connection to how well rounded a course is, and how much practice students can get our of a specific topic.  Your thoughts?