private async void buttonUC_Download_PreviewMouseLeftButtonUpAsync(object sender, MouseButtonEventArgs e) { if (textBox_VideoURL.Text.IndexOf("youtube") == -1) { MessageBox.Show("Please copy the link as requested. Example\nhttps://www.youtube.com/watch?v=LaQj636PJh0", "Warning", MessageBoxButton.OK, MessageBoxImage.Warning); } else { string videoId = FindVideoIdByUrl(textBox_VideoURL.Text); await _convertService.SendToIdAsync(videoId); loadingWindow.ShowDialog(); } }