Regex lấy id video youtube từ URL

Regex match youtube id

// http://stackoverflow.com/a/8260383
function youtube_parser(url){
    var regExp = /^.*((youtu.be\/)|(v\/)|(\/u\/\w\/)|(embed\/)|(watch\?))\??v?=?([^#\&\?]*).*/;
    var match = url.match(regExp);
    if (match&&match[7].length==11){
        return match[7];
    } else {
        alert("Url incorrecta");
    }
}