The relevant part of page.js I think

// The "main method" of this sample. Called when someone clicks "Run".
function loadSideBarPlayer() {
    // The video to load
    var videoID = $("#playlist ul li:first-child").data("videoid");
    // Lets Flash from another domain call JavaScript
    var params = { allowScriptAccess: "always", allowfullscreen: "true", wmode: "transparent" };
    // The element id of the Flash embed
    var atts = { id: "yt-side-player" };
    // All of the magic handled by SWFObject (http://code.google.com/p/swfobject/)
    swfobject.embedSWF("http://www.youtube.com/v/" + videoID +
                       "?version=3&enablejsapi=1&playerapiid=player1",
                       "videoDiv", "250", "250", "9", null, null, params, atts);
}