TAXI DRIVER AND PASSENGER DRIVE IN FRONT OF MANDALAY BAY HOTEL, SEE "AUTOMATIC WEAPONS FIRE" FROM 4TH FLOOR WINDOW, AND COMMENT ON IT LIKE YOU WOULD THE SOUP

WHY IS IT THE TAXI DRIVER AND HIS PASSENGER ARE NOT FREAKING OUT?

Someone grab this video for us, please, so we can keep a copy of it when it disappears.

Ah, here's a reasonable explanation from a comment at Youtube:

At 4:55, that is most likely a strobe light from the fire warning system that had been activated due to the gun smoke in the room on the 32nd floor where the shooter was located. A few seconds later, as the driver moves forward, you can see another strobe light. Whenever a fire alarm has been activated in a building, strobe lights throughout the building will flash to warn of an incident somewhere in the building. Standard protocol then is to standby for message through PA system informing as to what action to take.