The Vibration Trigger Option will trigger the camera whenever the device is shaken or disturbed.
The slider bar is used to set the sensitivity. Setting the sensitivity to 0 (zero) will trigger whenever a slight vibration is detected. Setting the slider midway will only trigger whenever a fairly large vibration is detected.
"Shot Interval" will determined the interval between each shot taken while the Vibration values remain constant. Set this to zero to only take one picture right when the Vibration sensor is triggered.
Here is how the Settings screen looks after purchasing the Vibration Trigger option: