If what the web page says is true, and there is no CGI or editing involved, then words simply can not describe this.
I stand in awe.
Quick update: It turns out that there is, in fact 1 second of CGI in the middle, as the muffler rolls across the floor. This was done because the entire setup wouldn't fit in the room, so it had to be broken into 2 parts. I don't think that diminishes the accomplishment.