Even with a proper exposure including a shutter speed as short as 30 seconds, a person walking in front of the camera won't show up unless they stand still. You can use that technique to take a picture through a busy sidewalk and see the people vanish on the image. The image also appears to be lit by a small work-light on camera right (note the hard shadow of the foot and the reflection on the man's helmet). He could have walked in the shadow and stopped in the light to increase that "vanishing" and reappearing effect (similar to how you might use a long shutter speed to blur a background while using a flash to "freeze" the subject).
Doing some back of the envelope calculations, with a somewhat bright room, you could take the exposure in anywhere from 15s to 2m which is plenty of time to walk across the room.
Of course all this is irrelevant because timers (mechanical and electronic) had been standard features in cameras for decades by 1996. It looks to me like he just moved in the midst of a 2 or 3 second exposure.
Doing some back of the envelope calculations, with a somewhat bright room, you could take the exposure in anywhere from 15s to 2m which is plenty of time to walk across the room.
Of course all this is irrelevant because timers (mechanical and electronic) had been standard features in cameras for decades by 1996. It looks to me like he just moved in the midst of a 2 or 3 second exposure.