--- a/dom/html/VideoDocument.cpp
+++ b/dom/html/VideoDocument.cpp
@@ -62,34 +62,34 @@ VideoDocument::StartDocumentLoad(const c
                                  nsIContentSink*     aSink)
 {
   nsresult rv =
     MediaDocument::StartDocumentLoad(aCommand, aChannel, aLoadGroup, aContainer,
                                      aDocListener, aReset, aSink);
   NS_ENSURE_SUCCESS(rv, rv);
 
   mStreamListener = new MediaDocumentStreamListener(this);
+  NS_ADDREF(*aDocListener = mStreamListener);
 
-  // Create synthetic document
-  rv = CreateSyntheticVideoDocument(aChannel,
-      getter_AddRefs(mStreamListener->mNextStream));
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  NS_ADDREF(*aDocListener = mStreamListener);
   return rv;
 }
 
 void
 VideoDocument::SetScriptGlobalObject(nsIScriptGlobalObject* aScriptGlobalObject)
 {
   // Set the script global object on the superclass before doing
   // anything that might require it....
   MediaDocument::SetScriptGlobalObject(aScriptGlobalObject);
 
   if (aScriptGlobalObject && !InitialSetupHasBeenDone()) {
+    // Create synthetic document
+    DebugOnly<nsresult> rv = CreateSyntheticVideoDocument(mChannel,
+        getter_AddRefs(mStreamListener->mNextStream));
+    NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create synthetic document");
+
     if (!nsContentUtils::IsChildOfSameType(this)) {
       LinkStylesheet(NS_LITERAL_STRING("resource://content-accessible/TopLevelVideoDocument.css"));
       LinkStylesheet(NS_LITERAL_STRING("chrome://global/skin/media/TopLevelVideoDocument.css"));
       LinkScript(NS_LITERAL_STRING("chrome://global/content/TopLevelVideoDocument.js"));
     }
     InitialSetupDone();
   }
 }