AS3 loading and controlling external SWF movie

programming flash
1

I’m able to load the actual external SWF movie, but I can’t seem to control it. I have already built a controller for my flash video player. The problem now is it only plays FLV and I want it to be able to take in SWF support. Again, I load the SWF fine, but controlling is the problem.

    function finished_loading (e:Event) {
        var externalMovie = MovieClip(swfLoader.content); // cast 'DisplayObject' to 'MovieClip'
        addChild(externalMovie); // add your swf directly to the stage
        externalMovie.gotoAndPlay("stop");
        trace("hi")
    }

    private function initSWF():void{
        swfLoader.load(new URLRequest("test_movie.swf"));
        addChild(swfLoader);
        swfLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, finished_loading);
        var externalMovie = swfLoader.content; // cast 'DisplayObject' to 'MovieClip'
        addChild(externalMovie); // add your swf directly to the stage
        swfLoader.gotoAndPlay("stop");
    }

I think this is the problem with the code. Casting it to a MovieClip only gives me a 1034 error.

Can someone help?
Thanks.