How do Ouija boards work? People sit around a board with letters and numbers on it, all touching a legged planchette that can slide around on the board. They pretend that spectral forces are moving the planchette around to spell messages. What's happening is that, at any given moment, someone is guiding the planchette, and the point is to make sure that the planchette always appears to everyone else to be moving under its own power.
Taking this idea to role-playing, the deluded notion is that Simulationist play will yield Story Now play without any specific attention on anyone's part to do so. The primary issue is to maintain the facade that "No one guides the planchette!" The participants must be devoted to the notion that stories don't need authors; they emerge from some ineffable confluence of Exploration per se. It's kind of a weird Illusionism perpetrated on one another, with everyone putting enormous value on maintaining the Black Curtain between them and everyone else.
That's exactly it, really, and I find that I like the description, as it captures the essence of what happens at the table, as I see it: one the one hand, although nobody says as much, what happens is purposive, and, at any given moment, somebody is controlling what happens and driving the action - sometimes the GM, but more usually a player, or all the players. They're "doing stuff", to put it bluntly. On the other hand, you get a "story" emerging from this process all the same, in a totally unpremeditated fashion, as a biproduct of that purposive behaviour, more or less by accident. And that isn't under the control of any one person at the table. It develops out of the ether of the interactions between all the participants and how they act within the game.
Of course, Ron Edwards is intending all of this as, basically, a description of bad gaming (he actually describes my view as that of "the most deluded role-player in the world"). Chiefly, this criticism seems to revolve around the failure to address "Premise", which is a concept he takes from Lajos Egri and which, even if you accept it as a useful tool in the context of dramatic writing, is not particularly suited to activities outside of that context. He also comes to the conclusion that people who experience ouija-board gaming are, basically, social retards who convince themselves they are enjoying themselves when they actually aren't, which I have to say I do not find incredibly persuasive. Then again, I am the most deluded role player in the world, after all.