Bookmarktlet that is supposed to download vimeo video, but doesn't work.and i know why.

bkmt.js

javascript: (function () {  
    var vim_id = document.URL.substring(17);
	var url = 'http://player.vimeo.com/play_redirect?quality=hd&codecs=h264&clip_id='
    +vim_id+
    '&time=1362143485&sig=e846af3c50137c059ea2099a220a1f8b&type=html5_desktop_local';
	saveToDisk(url, document.URL+'.mp4');
    console.log(url);

function saveToDisk(fileUrl, fileName) {
    var save = document.createElement("a");
    save.href = fileUrl;
    save.target = "_blank";
    save.download = fileName || fileUrl;
    var evt = document.createEvent('MouseEvents');
    evt.initMouseEvent('click', true, true, window, 1, 0, 0, 0, 0, false, false, false, false, 0, null);
    save.dispatchEvent(evt);
    (window.URL || window.webkitURL).revokeObjectURL(save.href)
    }
 }());