I've never heard of these "sessions" but I am a Firefly/Serenity fan. I own the 2-disc Serenity DVD and I love it. However, the USA loves to do double-dips (much more than here in Australia), so rest assured, you'll probably get a 2-disc or 3-disc Serenity DVD in November/December this year with more stuff than the Australian one. Still, in the meantime you could compile your own disc of stuff not included on any of the official releases.