A podcast is a free mean to diffuse audio and video files over the net. Each file is an episode. With subscription, you can receive new episodes. The SUPINFO Apple lab puts forward courses, didacticiels...
If I use iTunes, I just have to click on the "iTunes" link next the podcast name. If you don't want to use iTunes, click on the "RSS" link. It's the podcast RSS feed. The feed will be open in your favorite RSS reader.
You just have to use podcast RSS feeds. Click on one "RSS" podcast link. The feed will be open in your favorite RSS reader. You can download an episode doing a double-click on an episode or push "enter" after selected it.
If you don't know what is a RSS feed, wikipedia can help you. There are many RSS feeds players, for Mac OS, Linux or Windows. Le journal du Net. You can find one by clicking on the previous link.
The podcasts for iPod have files who can be import directly on an iPod video (or more). The others have best quality video on a computer but these videos must be convert to add them on an iPod.