The video below was shot by PircDrew. The first clip is the original clip unaltered. It is a little dark but still clear enough to see the shadow that comes into view from left to right in the doorway. Watch the doorway as Drew pans across the room. Just as the door nears the edge of the screen you first see something block the light then the dark shadow slowly enters the room and then backs out. The shadow can be seen on the door frame just above the black plug toward the end of the clip. (the light was the street light shining in through the bathroom window)https://www.pirc-ny.com/wp-content/uploads/2011/12/Darkshape-orig.mov
This next clip is the same as the original but slowed down significantly. The clip will run for quite some time and the shadow can be seen at the end of the clip. I left the clip intact so that you can examine the entire door in slow motion prior to the appearance of the shadow.https://www.pirc-ny.com/wp-content/uploads/2011/12/dark-shape-slow.mov
The last clip is in slow motion and has been lightened significantly. I also marked where you should be looking just before the shadow comes into frame.
I normally would not mix still photos & video but these are captures from the video presented. One shows the door with no shadow the other shows the shadow. The stills have been lightened to make them easier to view.
Shadow not visible here Shadow Visible