It's difficult to say with any certainty what we're seeing in this video. We definitely see a shadow cross the field of view, but without knowing the complete layout of the pub we cannot know what might possibly be passing in front of a light source to create it. The video is apparently is recorded in "night shot" mode in relative darkness, which might eliminate the idea of a conventional shadow. The dark form does roughly have the shape and size of a person. The flash of light, however, I suspect was caused by one of the investigators with a flashlight. What do you think?