Most people "in the know" would say that the definition of a "podcast" is a time-sequenced, rolling list of audio files in RSS 2.0 format. Podcasts were originally called "audio blogs". And blogs, by definition (I think), are available in RSS or ATOM format, both of which are XML-formatted file specifications. All blogs are also available on the web in HTML format.
Most people still read blogs and listen to podcasts through the web page set up by the feed producer. This MAY have changed for podcasts with iTunes, which recently added podcast support through RSS 2.0 and special RSS extensions. So while the main method of reading/listening/watching blogs and podcasts and videocasts may currently be through HTML, I expect this will slowly change as we all move toward aggregators making it easier to read, watch, and listen.
The bottom line is that aggregators make it much easier and faster to access all this information, once you "subscribe" to the feeds you enjoy, you don't have to go back and check each web page every time. And it doesn't matter what format it is in: text, audio, or video. An aggregator will make checking faster for anyone, even those with a small number of feeds, say two or three. At the other end of the scale, it's just not practical to check a larger number of websites when you get to about 15-25 sites/feeds. At this point, an aggregator is (almost) required to be able to keep up with all the sites every day.
I posted this longer explaination because I think we both agree it is not all one way or the other (aggregator vs. HTML). Many people will be happy with randomly checking their list of 20 web sites to manually check for the latest posts. Some web sites they will check daily, others they will check weekly. Other people want an easy way to be updated on all of them every morning. An aggregator works great for this.
And even among the aggregator crowd, some will want to download to their desktop, and transfer the audio or video to their Pocket PC (or other Portable Device), and others will want to download all news, blogs, audio, video, podcasts directly to their Pocket PC without ever using a desktop computer. FeederReader is for this group!
Greg Smith
Author, FeederReader - Pocket PC *direct* RSS text, audio, video, podcasts
www.FeederReader.com - Download on the Road