The correct, updated links for all the videos are at this site.
Dear All (including students enrolled for credit and other who are following the discussion online):
The comments remain open. If your comment is to a particular author, please post it as a comment on their paper. If it is for more several authors, it is best to post multiply, to each author, if you want a reply. If you just want to register the comment, you can do it on the discussion section for the day.