The easiest explanation in my mind is that they planned to remove the camera so it didn't capture whatever vehicle they used to take NG away.Why did he even approach the enclosed brick vestibule? has been something I have mulled over.
Even if they didn't pull the vehicle into the driveway they couldn't have been certain the camera couldn't see the street
I also feel like they may not have wanted to pull the vehicle into the driveway until NG was secured, but I could go both ways on that point