I believe that Coursera courses are popular exactly because they only allow watching archives if you have signed up before. What I mean is people sign up to a l

I believe that Coursera courses are popular exactly because they only allow watching archives if you have signed up before. What I mean is people sign up to a large number of courses, just for being able to view the course any time in the future. This also means that Coursera courses have naturally the highest "total enrollment" numbers, even though probably only a few percent of the students are actually taking the class.