Alright, I have been doing a little research of my own and I found at least one point that contradicts the two documentaries above and it is from a highly credible source unlike the two above: The steel grade that was used in the WTC towers would loose 90% of its strength after being exposed to temperature above 1000 degrees for the period of 15 minutes. We know well that the temperature inside the buildings were well above ( around 3000-3500 degrees, and even the two documentaries mention it) and it burned more than 15 minutes.