9-11, give me a break.

[Huggy Bear]

Please explain how this molten metal located near the top of this huge skyscraper caused the building to collapse in on itself the way it did? I genuinely want to know.

A demolition team couldn't have done a better job.

There's no mystical science at work here. Hot steel looses its structural integrity at temperatures much lower than those of burning jet fuel (even below 1000F), there's no need for the steel to melt. Once it has softened to a certain point, it can no longer support the weight of the floors above, when the collapse begins, physics (i.e. gravity) takes over and the building falls vertically, the floors below cannot support the force of the collapsing portions on top. As the reaction continues, the inertia of the falling building only increases. 

I'm not sure what people expect, why would the building suddenly fall in a different direction than the force of gravity (towards the earth's core)?

*emphasis mine*

https://m.youtube.com/?#/watch?v=lO9kAw3GR3A