First, make sure the individual video clips are not protected against deletion. The  key icon indicates that a clip is protected. Should this be the case, it is likely that the sensitivity of the G-Sensor is too high and the camera has locked the recordings, for example, due to the camera handling high ratio disparities. The sensitivity of the G-Sensor can be adjusted in the menu. If recordings are unlocked and the camera still does not erase previous clips, then the firmware should be updated. This firmware, including instructions, can be downloaded from the product pages on our website. If this does not help, please contact our customer service.