Choose the type of subject to which the camera gives priority when focusing in video mode (Choosing a Subject Type for Autofocus).
AF When Subject Not Detected
Choose whether the camera focuses if unable to detect a subject of the type selected for  when [ ] is selected for focus mode.
If  is selected, the camera will initiate autofocus whether or not a subject of the selected type is detected.
Select  to disable autofocus when no subject of the selected type is detected.