/* This is a private function. */
function createYoutubeEmbedding(root, video_id)
{
    // <div class="videoblock"><object data="' + url + '" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"><param name="movie" value="' + url + '"></param><param name="wmode" value="transparent"></param></object></div>
    var oDiv=root.appendChild(document.createElement("div"));
    with(oDiv) { className="videoblock"; }
    var oObject=oDiv.appendChild(document.createElement("object"));
    with(oObject)
    {
        data="http://www.youtube.com/v/" + video_id;
        type="application/x-shockwave-flash";
        wmode="transparent";
        width="425";
        height="350";
    }
    var oParam=oObject.appendChild(document.createElement("param"));
    with(oParam) { name="movie"; value="http://www.youtube.com/v/" + video_id; }
    var oParam=oObject.appendChild(document.createElement("param"));
    with(oParam) { name="wmode"; value="transparent"; }
}

/* Use this function to clear a given element. */
function clearElement (elem)
{
    elem.textContent = "";
}

/* Use this function to clear a given element by name. */
function clearVideo (elem_name)
{
    var elem = document.getElementById(elem_name);
    clearElement(elem);
}

/* Use this function to embed youtube videos. */
function embedYoutube (elem_name, video_id)
{
    var elem = document.getElementById(elem_name);
    clearElement(elem);
    createYoutubeEmbedding(elem, video_id);
}