What to do when a professor hasn't uploaded course content for an online class?
What does the syllabus say about when the lecture will be posted? It should say something like "Lectures posted every Sunday", etc. 
What you should do is copy and paste the discussion board items where students complained, and his response that he acknowledges that he missed his own deadlines, and email it to the Associate Dean (or Dean if there is no Associate Dean). One of the duties of the Associate Dean is to help students with these type of problems.
In your email to his "boss", be professional and fact-based. Merely state that the professors has not posted the lectures (fact), and you wish to have them so you can keep up (the impact to you). Don't say it so negatively that the Dean feels he has to stick up for the Prof (i.e defend the university).
Remember the goal is that you want the lectures posted. No matter how pissed you're at the Prof, don't try to "take him down". You just want the lectures, but at the same time you don't want a angry prof who'll nitpick your Final Exam answers? You can achieve your results with politeness and tact.