If you find that your DVD is being swallowed up by your Myth box and the eject button fails to return it after it has been ripped, then try adding an 'Eject' button to your menu.
This is quite easy to do. Simply add the following to /usr/share/mythtv/dvdmenu.xml and /usr/share/mythtv/optical_menu.xml:
<button> <type>DVD_EJECT</type> <text>Eject DVD</text> <action>EXEC eject</action> </button>
Now you should be able to retrieve your DVD without resorting to the keyboard.