For some unknown reason, the 9/11 conspiracy theorist phrase "jet fuel can't melt steel beams" has become one of the biggest memes on the internet in 2015. The assertion comes from the fact that because jet fuel burns at 1,500 degrees and steel melts at 2,750 degrees, the attacks on September 11, 2001 must have been a conspiracy.
Well, one blacksmith had enough of seeing the meme online, and decided to make a video showing that the temperature of jet fuel, which indeed cannot melt steel beams, can significantly weaken them to the point where the structure would become unstable and collapse.
Mild language warning
So there you have it.