Visitor A enters the room. He stands still for a short time. His shadow has been captured and is now projected on the wall. Visitor A has left the room, his shadow is still projected. Visitor B enters the room. The projected shadow from A and the real shadow from B are visible.
Visitor B hasn't also moved for a short time, now his shadow is also being captured and projected. The projected shadow from A starts to transform. Both shadows are transforming. Both shadows fade away.
The visitor enters the room. Due to the light of the video-beamer (always turned on), every person throws a shadow on the beamer's opposite white wall. The moment the visitor stands still for 3 seconds or longer, his shadow is frozen.

As soon as the visitor moves again, the picture of his shadow stays at the wall. Logically, the "real" shadow moves with the person, the "unreal" stays on the wall.

After an undefined period of time the shadow starts to transform in an undefined way. If there are several persons in the room it could be possible for the shadows to overlap.