Of course they did not come with any assignments, just like these courses. Can't blame them, but other universities offer much resources -- for the same topic, you can often find a course offered by another university that provides videos hosted on YouTube, full assignments and labs, even exams. The only thing you are missing is TA/office hours and the course credit. In other words, unless you actually want to earn credits and work towards a degree, I suggest that you skip OMSCS videos unless there is no alternative.