The last setting is "Break at end". The default is True and it means that the controller will try its best to keep the motor at place.
The controller is sending current to the motor in order to keep it at place. The controller is applying electrical break to the motor.
Even if we apply enough power to turn the motor by hand, it will return to its initial position.
When set to false, no such behavior is present - the motor can freely rotate and the robot slowly coasts to a resting position.
This is a companion discussion topic for the original entry at http://www.fllcasts.com/episodes/409-ev3-phi-teacher-notes-break-at-the-end-option-in-ev3-g-for-mindstorms-move-block