I wanted to download these Stanford and MIT lectures. Unfortunately, they are all privatized by iMac. Do you see that all download links bring to itunes.com site? BTW, why are all the best world universities are subsumed by Apple? I have installed the iTunes, but I still do not see the Download button. All it does is play online.
Here is how the iTunes download page looks like 
You may enjoy the DPI-aware perfect Mac interface. But, where is the "Download" button?
Best Answer
If you want to stay up with the entire course, press the large subscribe button and you will then get a warning that explains a bit more about how the process works.
At that point, you can double check what content you want to actually download (just like a podcast works) and you will of course have to enter an AppleID with payment set up if the specific course you have chosen requires such for some or all of the materials.
You can also press the free buttons along the right to download individual lessons to your computer (or iOS device) for offline viewing.