In one of the previous MooC discussions some people indicated that they felt guilty for not finishing classes, which might be a deterrent.

I think there is value in having someone pick good ones, so you don't waste time starting things that are poorly recorded, etc.

The site up thread is good for this- https://www.class-central.com/

My project (https://www.findlectures.com) is built to help discover standalone lectures (conference talks, etc), which I hope helps the people who feel guilty not finishing stuff :)