(Mac OS X) Camera Sequencer support on 64-bit systems is limited. For better performance and real-time results, run Maya in 32-bit mode to use the Camera Sequencer.
By default, Maya creates the shot using the active camera in the current panel. The shot is inserted at the current sequencer playback time (where the red playback indicator displays in the Sequence Editor) and sets the start and end frame range based on the Maya Time Range Slider.
When you create a shot using the toolbar, the shot uses the current Maya playback start and end times as the starting and ending Maya times of the shot, and the shot is placed in the sequence beginning at the current sequence time.
You can set a double-click behavior preference for camera shots in the Preferences window. See Camera Sequencer preferences.