private void ShowVideo(Uri uri)
{
_isShowingMedia = true;
VideoControl.Opacity = 1;
if (VideoControl.MediaPlayer == null)
{
VideoControl.SetMediaPlayer(_mediaPlayer);
}
VideoControl.MediaPlayer.Source = null;
VideoControl.UriSource = uri;
VideoControl.MediaPlayer.PlaybackSession.PositionChanged -= OnPlaybackPosChanged;
VideoControl.MediaPlayer.PlaybackSession.PositionChanged += OnPlaybackPosChanged;
VideoControl.Activate();
}