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The lasers start at about 0:27 and last until about 0:55 in the video, which is 3 minutes 12 seconds long. A few times, the lasers appeared to go directly into the crowd — or at least towards the camera that captured the show.
As the biplane lands, starting at about 2:29 the laser projector can be seen as a square black box mounted above the top wing.
The show was created by Scandinavian Airshow. The company says "The Catwalk is the ultimate air show aircraft and can in the evening transform into a pyrotechnic platform and perform its amazing night pyrotechnic display." There is no mention of lasers on their Catwalk webpage as of March 12 2019, so this may be a relatively new addition.
As one YouTube commenter wrote, "That's hella ironic if a plane is shooting lasers at you 😂"
From YouTube, via BGR