We already mentioned the FOSDEM 2012 role playing game development talk but recently I found links to more open source game development and game design "devrooms" here.

• Alistair Riddoch - The Dynamic Data Driven Worlds of WorldForge.mp3
• Arthur Huillet - Anatomy of a role playing game.avi
• Erik Ogenvik - Getting Started With Ogre3d For Game Development.mp3
• Jeremy Rosen - Balancing a game - the open source way.mp3
• Thomas Kinnen - Data-Driven and Component-Based Game-Entities.mp3

I also recommend "A New OSI for A New Decade" here, which starts with explaining how not to be annoying when advocating freedom.