In most dashcams with GPS, the GPS receiver is incorporated into the holder. A GPS receiver processed in the holder has better reception and is also more compact and less conspicuous. In dashcams where no GPS holder or receiver is supplied as standard, you can use these to keep track of the locations and speed of the trips. You can view the locations later on the PC with special software and the speed is displayed at the bottom of the videos.
An additional holder or GPS receiver can be useful to use your dashcam in multiple vehicles. This is because the GPS is glued to the windscreen and is therefore usually not easy to remove. You simply slide or click the dashcam onto the GPS holder so you can easily remove the dashcam from the car.