Android Video player not worke on device & emulator????

Question

Uri uri = Uri.parse("http://video.ted.com/talks/podcast/MichelleObama_2009P.mp4");
VideoView videoView = (VideoView) findViewById(R.id.surface);             videoView.bringToFront();
    videoView.setVideoURI(uri);
    mediaController = new MediaController(this);
    mediaController.setAnchorView(videoView);
    videoView.setMediaController(mediaController);
    videoView.requestFocus();
    videoView.start();

Any help greatly appreciated ??? Thanks...