All of the lectures have been posted as well as solutions to HWs 2 and 3.
http://public.research.att.com/~volinsky/netflix/sigkddexp.pdf has a nice discussion about the Netflix challenge. The ‘rematch’ was canceled over privacy concerns, but the first one was completed and the $1M reward was given out.
This paper details a method by which using both the Netflix Challenge dataset and reviews from IMDB they were able to figure out the identities of some of the users!
Finally, you can look at the distribution of certain movie rentals in various cities on this NYT interactive page. As always, feel free to email the staff any questions that you have about the course content!