Ever seen a train lay its own track? [video]

From http://ycombinator.com/newsguidelines.html :

    In Submissions

    ... If you submit a link to a video or pdf,
    please warn us by appending [video] or [pdf]
    to the title.

I've just had to hunt through 50 tabs in 3 browser windows on 2 desktops to find the auto-starting video. Please warn us.

Thanks.

Is there any context for this video?