To Halo Fans:

I watched the video, but I don't quite get where the bots come in to play. It looked to me like they were just putting a bunch of characters from the single-player campaign into Rat's Nest. They weren't moving around or trying to kill the narrator, I think someone jumped to some extremely far-fetched conclusions on that one.

As for the map editor, it does indeed look like it was exactly that. Can't wait.