It looks like the black mist video sent by a viewer shows just the basement Christmas tree lights and illumination of the back wall being obscured by passage of a shadow from left to right, over and over. Can you confirm this is not an electrical effect to limit and restore power to the tree, over and over, as with a dimmer?

This is not just a dimming of the Christmas tree lights. They are continuing to shine steadily. What is happening is there is an energy preventing light from the area around the tree in reaching the camera. So a black mist passing in front of the tree is an accurate description of what is captured electronically. It is the interposition of spirit energy being recorded as this group of lost soul spirits carries out a kind of steady looping of their location.