I am unable to add video controls to the Android video player

I am unable to add video controls (i.e. play, stop, fast-forward) to the video player for a Xamarin.Forms app.

The video plays fine. However, they're no controls for a user to control the video player.

Specifically, I receive a null exception when I attempt to execute the following statement:

_mediaController.Show(5000);

Any ideas on how to implement this trivial functionality?

Video Renderer

public class VideoViewRenderer : ViewRenderer<VideoView, Android.Widget.VideoView>, ISurfaceHolderCallback
{
    Android.Widget.VideoView _videoview = null;
    MediaPlayer _player = null;
    CustomMediaController _mediaController = null;

    public void SurfaceChanged(ISurfaceHolder holder, global::Android.Graphics.Format format, int width, int height)
    {

    }

    public void SurfaceCreated(ISurfaceHolder holder)
    {
        _player.SetDisplay(holder);

        _player.Prepare();
        _player.Start();
    }

    public void SurfaceDestroyed(ISurfaceHolder holder)
    {

    }

    protected override void OnElementChanged(ElementChangedEventArgs<VideoCommentary.VideoView> e)
    {
        base.OnElementChanged(e);
        e.NewElement.StopAction = () =>
            {
                _player.Stop();
                this.Control.StopPlayback();
            };

        _videoview = new Android.Widget.VideoView(Context);

        _mediaController = new CustomMediaController(Forms.Context, false);
        _mediaController.SetAnchorView(_videoview);
        _mediaController.SetMinimumWidth(_videoview.Width);
        _mediaController.RequestFocus(); //will make it display as soon as the video starts                    
        _videoview.SetMediaController(_mediaController);
        _mediaController.Show(5000);

        base.SetNativeControl(_videoview);
        Control.Holder.AddCallback(this);
        _player = new MediaPlayer();
        play(e.NewElement.FileSource);
    }

    void play(string fullPath)
    {
        var assetFileDescriptor = Forms.Context.Assets.OpenFd(fullPath);

        if (assetFileDescriptor != null)
        {
            _player.SetDataSource(assetFileDescriptor.FileDescriptor, assetFileDescriptor.StartOffset, assetFileDescriptor.Length);
            _player.Prepare();
            _player.Start();
            Control.Layout(0, 200, _player.VideoHeight, _player.VideoWidth);
        }
    }
}

Custom Media Controller

public class CustomMediaController : MediaController
{
    public CustomMediaController(Context context, bool b) : base(context, false) { }

    public override void Hide() { }       //this will make controller not to disappear after interaction
    public override void Show()
    {
        base.Show();
    }
}