需求是点击按钮后，弹出弹窗播放视频。按钮的点击事件如下。

public void ShowVideo(){    Window window = new Window();    window.Width = 800;    window.Height = 600;        // 控制弹出位置在屏幕正中    double screenHeight = SystemParameters.FullPrimaryScreenHeight;    double screenWidth = SystemParameters.FullPrimaryScreenWidth;    window.Top = (screenHeight - window.Height) / 2;    window.Left = (screenWidth - window.Width) / 2;    MediaElement player = new MediaElement();    //player.Margin = new Thickness(1, 1, 1, 1);    player.Width = 800;    player.Height = 600; 　　// 视频资源放在Debug\bin目录下    var mp4_path = AppDomain.CurrentDomain.BaseDirectory + @"\video.mp4";    player.Source = new Uri(mp4_path, UriKind.RelativeOrAbsolute);    player.LoadedBehavior = MediaState.Manual;    player.Stop();    player.Play();    // 视频播放控件加入到窗体中    window.Content = player;    window.ShowDialog();}

运行效果如下：