Bookmarklet: display maximum resolution YouTube thumbnail

YouThumb

javascript: function gqv(v) {
    var q = window.location.search.substring(1);
    var vars = q.split("&");
    for (var i = 0; i < vars.length; i++) {
        var pair = vars[i].split("=");
        if (pair[0] == v) {
            return pair[1];
        }
    }
    return (false);
}
window.location = 'http://img.youtube.com/vi/' + gqv('v') + '/maxresdefault.jpg';