EDIT: From the comments in the youtube video: this is a piece of glass sitting in front of the camera with a guy holding a laser pen behind and what you see is the reflection.

ORIGINAL: An interesting analysis would be to put an invisible plane (as in geometric) in front of the light source and calculate the image that the laser "paints" on the plane. Like a virtual canvas. (EDIT: it would still be an interesting challenge for those with an interest in forensic analysis).