There is a substantive difference between the service offered by iTunes U, Youtube, and countless others, and the service offered by Coursera and edX. This difference corresponds to a difference in learning styles (synchronous v. asynchronous, as it has been phrased in this thread), and it doesn't make sense for any one product to target two diametrically opposed learning styles. What does make sense is the approach that Coursera has actually already been taking: offer both as separate products. You can take classes on schedule, or you can take them off schedule for no certificate. Complaining about the synchronous model because you are an asynchronous learner simply doesn't make any sense.