Shadow Ghost Video?

The following ghost video has a slow dark mass moving in front of the lens. Watch the center of the frame. Is it a shadow ghost or did the person running the video accidentally move a finger in front of the lens?

It would appear that the mist "oozes" into place, something dissimilar to an appendage sliding in the way. This video from Ghost Tracers is at least worth consideration. You decide what's going on in it!