content: Watch the documentary that was aired on the National Geo or Discovery channel of experts looking into the claims made in this video and they explain it all and conclude that the planes brought it down. But you arm-chair experts know more, bull crap.The floors of the towers were made of concrete, which were VERY heavy, just a few weakened steal beams as seen on the news is all it would take. The weight of the upper floors on those beams caused the upper floors to come crashing down upon the floor that was hit and caused a domino effect of ever increasing weight that just smashed the towers.Use some brains people.