Yahoo! have posted a nice instruction set on their blog, detailing how to subscribe your copy of iTunes to video searches of interest so that you are constantly fed relevant updated video casts!
Basically, to do it you simply use the RSS url generator to generate the RSS feed for your video search, add that to iTunes and watch the videos as they arrive in iTunes (or if you have one of the new Video iPods, you can watch them on that!).
I will be talking about other uses for RSS tomorrow evening at the IT@Cork RSS event – hope to see you there!