Richard Stallman discusses the political philosophy of Free Software. I (Vinay Gupta) found this talk a great education, and encourage you to listen to it as if you're encountering the concept of Open Source for the first time (yes, Stallman spends quite a bit of time distinguishing Free Software from Open Source, and it's a much more important distinction than I had realized.)
(Technical note: audio and video on this page is set up using HTML5+OGG. Firefox and Chrome handle this correctly. If you have to download the .ogg files to view/listen, use VLC. All tools are cross-platform and FOSS.)