Of the podcast directories listed I found Podnova and PodcastAlley reasonably easy to search. Under Podnova I found some American library vidcasts of lectures to the library community. Under PodcastAlley I found History according to Bob, which tells fascinating stories of history's people, places and cultures. I pulled this feed to my Bloglines account.
I also searched under iTunes for comedy and found a vidcast by John Cleese, but I couldn't get it across to my Bloglines.
Another interesting exercise, which took a lot of time, and was a bit frustrating. I don't think I will use this much.