This footage shows customers running for their lives as the floor at a building materials shop in Russia collapses under their feet. https://filedn.eu/lhVNGNsizwl5t7THnzzJ2c8/CEN-CollapsedFloor-01.mp4 The video shows the shoppers and staff narrowly avoiding falling through the gaping hole that opens up beneath them and being crushed by falling boxes. For one…