At Dnr TV there are two episodes with JP Boodhoo, where he gives an introduction to test driven development:
If you want to see unit testing and TDD used together with a whole bunch of other agile practices, I would recommend watching the sceencast series Autumn of Agile. This series shows the development of a fully unit tested application from start to finish.
As for podcasts, check out the following:
Since mock objects are a quite important part of unit testing, these podcast episodes might be of interest as well:
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
