I have the BV 650 2CH installed on our ML. Once you have the app on your phone you can view the footage BUT only whilst the camera is on and you are connected to it via the cameras wi-fi. I enquired with BV regarding watching footage remotely (eg I am not in the car, whilst someone else is driving, parked up somewhere etc) and this was the response I got:
"The camera has a Wi-Fi connection that must be connected to the cloud. To do that you will need to either use your mobile phone a s a wireless hotspot or purchase a 4G/ Wi Fi dongle form say EE and provide a permanent 4G connection to your car"
This was for my model of cam, but I would imagine yours would be similar if not the same. I have never bothered doing it TBH, it does what I needed it to do, ie record on the move and footage stored on the app should I need it.