I'll second Taruns answer of google video & CodingQA - the CodingQA guys are a really likeable duo just putting their ideas across. they don't claim to be experts, just imparting knowledge on how they operate & their understanding of testing methodologies.
I find itunes proves more fruitful if you search for actual topics, as opposed to high level subject areas.
My search for "agile testing" & "software testing" turned up limited results, but when I searched for things like "exploratory testing", "james bach", "Cem Kaner", "James Whittaker" I had better luck.
I try to search for podcasts which will answer a question I'm currently rolling around in my head - for example, I'm currently learning about exploratory testing & after searching around google I now have a range of buzzwords (see above) which I search for in itunes.