Halo 2 Vista is also still online and it might be continued much further now (according to a tweet by BSAngel). And as we are on forge forums I´d suggest you look into that first as H2V has lots of good custom content available easily (new maps, weapons, sp missions etc). Check out h2pc.org!
This has been known for a while. I assume the video you found was Arbiter 617's? Would make sense considering he just uploaded a video regarding it a couple days ago... Anyway, it's definitely pretty cool. Makes me wish I had all the cords needed to make it work :/
Meh, your better off buying Halo 2 Vista for PC. It works on Windows 7 in case you don't know. There's achievements as well, plus like mentioned above custom player maps.