Wi-Phi's mission is to introduce people to the practice of philosophy by making videos that are freely available in a form that is entertaining, interesting and accessible to people with no background in the subject.
There are now a number of high quality podcasts focused on philosophical topics. Several of these podcasts have episodes with excellent overviews and introductions to key topics in the history of philosophy and contemporary philosophy. As with most podcasts, you can either subscribe to the feed, to receive the latest episodes, or go back through the archive to listen to earlier episodes.