Collapse of steel structure

This video shows the collapse of the steel structure, probably due to the inadequate design of the structure. This video shows two important phenomena for engineers, that structure can collapse under their own dead load if they are not properly designed as in this video the structure failed during the installation. Secondly, shows the ductility of the steel structure while collapsing and giving enough time to realize that structure is falling. There might be other possible reasons for the collapse, please comment if you can think of other causes of failure. Hopefully, no one is hurt in this video.