FWIW, their FAQ section states specifically ...
"Can I mirror some or all of the site?
Sure. Actually, we'd be your new best friend if you could mirror some or all of our course materials. But be warned, it takes a lot of hard drive space and a lot of bandwidth - we currently have almost 80 gigs of material (mostly lecture videos) and during the school year we got an average of 10 gigs/day of downloads. "