In general, I've found the forums on MOOCs pretty useless other than for dealing with specific technical issues with the course itself. They just don't scale well and there's a huge disparity in the level of the participants a lot of the time. In programming courses, you've got some people asking about some nuance of an algorithm while others aren't sure how to install a text editor. Any course built around having meaningful discussions in the forums has been a tire fire in my experience.

Automated code checkers are definitely useful but, other than that, I'm not sure I've found MOOCs much different from watching YouTube videos. Nothing wrong with that--especially with top-flight lecturers--but they're hardly revolutionary. Videos of lectures have pretty much been a solved problem since VCRs went mainstream.