--- a/b2g/components/YoutubeProtocolHandler.js
+++ b/b2g/components/YoutubeProtocolHandler.js
@@ -88,17 +88,17 @@ YoutubeProtocolHandler.prototype = {
       streams.forEach(function(aStream) {
         let params = extractParameters(aStream);
         let url = params["url"];
         let type = params["type"] ? params["type"].split(";")[0] : null;
 
         let index;
         if (url && type && ((index = recognizedTypes.indexOf(type)) != -1) &&
             index > bestType) {
-          uri = url;
+          uri = url + '&signature=' + (params["sig"] ? params['sig'] : '');
           mimeType = type;
           bestType = index;
         }
         for (let param in params) {
           if (["thumbnail_url", "length_seconds", "title"].indexOf(param) != -1) {
             extras[param] = decodeURIComponent(params[param]);
           }
         }