Ok, so you do need a large roaming distance. But if your machine has room for that much roaming, then there really is no problem with what its currently doing, right? When any of the four nozzles is over the camera, they are all within the roaming distance so it should be safe for any/all of them to be below safe Z. It is a little hard to tell from your video, but at least in the log file, it appears all nozzles are lifted to safe Z before they move away from the camera.