If you follow that link you get to the HD versions of the videos in iTunes. That's a huge amount to download. If you click the "Developer on iTunes" breadcrumb on the upper right, you can get to the SD versions.
I notice there are only 210 SD tracks, compared to 224 HD ones. ("Tracks" seem to include the PDFs of the slides, so really it's about 110 videos.) I don't know what's missing on the SD side. I plan to download both sets, starting with SD so I'll have a complete set that much sooner.
Doing a Get Info in Finder, I see in 2010 the HD videos were about 32GB total, compared to 14GB for SD. Big difference. In 2011 the HD they must have increased the resolution, because the HD was about 53GB.
--Andy