Actually the Falloff node is not dependant or influenced by the light like you say at 7:52. It is dependant on the angle of the polygon to the camera. The more the polygon is facing to the camera the more white it gets, the more it is facing away from the camera, the more black it gets. You can compare it to the fresnel shader of standard c4d material. you can observe this phenomenom in nature when you look to a lake for example: if you look in the distance the water surface reflection is strong and you can't look through the water. but if you sit in a boot and look straight down on the water the reflection is less and you might be able to look through the water.
