If you want to see it in action, here is a thread full of videos where you can see it: http://forums.penny-arcade.com/showthread.php?t=54678
HOW DO I WORK IT?
--- You just post links to youtube videos like you normally would. The system takes care of the rest.
WHY IS IT EXPERIMENTAL?
--- the magic that makes it work means that every single post gets regex matched searching for video links that can be replaced with inline video (whether they have video links or not). This means additional load on the servers. I don't know how much
additional load we are talking about, without trying it. This is why I sat on this for several months even though it was a simple install. Because for the first 3 months of this year we had performance issues I didn't want to exacerbate.
I DON'T WANT INLINE VIDEO, CAN I OPT-OUT?
--- not yet, but if enough people ask for it, it is something which should be pretty doable. So if you want to be able to opt-out, please let me know here in this thread.