I just found a great tool on GitHub, written in Python, named edx-dl that is
currently downloading an edX course, including all videos. You can get it at
<https://github.com/coursera-dl/edx-dl>. I haven't tried viewing the course
offline yet, but it has a command that you type in, giving your user name. It
prompts for your password. It has an option that then lists all the courses
you're registered for and it did that correctly for me. I suggest this tool
for downloading edX courses. But, I won't actually send this message until
I've checked if I can view the course offline.

OK, well good news and bad news. It appears that it downloads just the videos
themselves. That is good enough for me - they're in separate folders by
lesson, etc., so I don't really need the individual web pages. Still, that
would have been nice. The Chinese lesson I'm subscribed to has pages with
links to individual audio files which this app did not download.