Have you tried something like this?
sender, RoutedEventArgs e)
HyperlinkButton button = (HyperlinkButton)sender;
button.Visibility = button.Tag ? System.Windows.Visibility.Collapsed : System.Windows.Visibility.Visible;
//Or you can do this, its the same as the above statement
button.Visibility = System.Windows.Visibility.Collapsed;
button.Visibility = System.Windows.Visibility.Visible;
This way you provide a return to visibility if present. Also you should consider how often this event is firing. You may want to use it inside the coverflow's SelectionChanged event