用法

private string _videoPath;

//打开按钮
private void ButtonOpen_Click(object sender, RoutedEventArgs e)
{
    OpenFileDialog dialog = new OpenFileDialog();

    dialog.Filter = "Video File(*.avi;*.mp4;*.mkv;*.wav;*.rmvb)|*.avi;*.mp4;*.mkv;*.wav;*.rmvb|All File(*.*)|*.*";

    if(dialog.ShowDialog().GetValueOrDefault())
    {
        _videoPath = dialog.FileName;
    }
}

//播放按钮
private void ButtonPlay_Click(object sender, RoutedEventArgs e)
{
    MediaPlayer.Source = new Uri(_videoPath);

    MediaPlayer.Play();
}

private void ButtonStop_Click(object sender, RoutedEventArgs e)
{
    MediaPlayer.Stop();
}

private void ButtonForward_Click(object sender, RoutedEventArgs e)
{
    MediaPlayer.Position = MediaPlayer.Position + TimeSpan.FromSeconds(20);
}

private void ButtonBack_Click(object sender, RoutedEventArgs e)
{
    MediaPlayer.Position = MediaPlayer.Position - TimeSpan.FromSeconds(20);
}

private void MediaPlayer_MediaOpened(object sender, RoutedEventArgs e)
{
    // Get the lenght of the video
    int duration = MediaPlayer.NaturalDuration.TimeSpan.Seconds;
}

WPF播放视频、WPF_MediaElement用法