Ask HN: Good online course on operating systems?

I have some glaring gaps in my CS knowledge that I have been having fun filling. Next up is one of the biggies, either operating systems or compilers.

There is a Coursera compilers course which looks decent but nothing for operating systems on Coursera, Udacity etc. There are courses from Stanford, Columbia and Berkeley with some resources online, but none seem to have video...

So how about it, can you recommend a course, or failing that a textbook?

Thanks!