Two buttons on the Player toolbar, Visible and Show in Layout, sound similar but have different functionality. Making a player visible means that it will be visible when the mbedlet runs. It is the same property that you can set in the player's Property sheet. However, some players can never be visible - a path for instance. But you still need to see the path to edit it, right? That's where Show in Layout comes in. Show in Layout enables you to see any player in the Layout window.
Above you see the Layout window. Note you can see the path, text (Your Name Here), and both buttons because we clicked Show in Layout for those players. Now look at the Runtime window below.
In the Runtime you only see the buttons. Why? Because the button players are the only ones with their Visible property set to true.