--- a/browser/base/content/nsContextMenu.js
+++ b/browser/base/content/nsContextMenu.js
@@ -849,17 +849,17 @@ nsContextMenu.prototype = {
     if (!name)
       name = "snapshot.jpg";
     var video = this.target;
     var canvas = document.createElementNS("http://www.w3.org/1999/xhtml", "canvas");
     canvas.width = video.videoWidth;
     canvas.height = video.videoHeight;
     var ctxDraw = canvas.getContext("2d");
     ctxDraw.drawImage(video, 0, 0);
-    saveImageURL(canvas.toDataURL("image/jpg", ""), name, "SaveImageTitle", true, false, document.documentURIObject);
+    saveImageURL(canvas.toDataURL("image/jpeg", ""), name, "SaveImageTitle", true, false, document.documentURIObject);
   },
 
   fullScreenVideo: function () {
     this.target.pause();
 
     openDialog("chrome://browser/content/fullscreen-video.xhtml",
                "", "chrome,centerscreen,dialog=no", this.target);
   },