As Science Reporter Peter Hadfield advises, check the source and the reliability of the cite.
http://www.youtube.com/watch?v=LdnZ1l5TxJk&feature=relmfu
So, to begin with, who is one of the experts mentioned in the video? There is a well renown biologist: Lynn Margulis…
Wait, you can not see a problem here already? Are you saying that a Biologist is like an Architect or an Engineer?
Well that is a red flag, but not a show stopper, what is what she claimed took place on 911? Funny, she points out that evidence was removed from the scene of the crime so science could not be done, then she points that scientific evidence shows that red/grey crystals were found that point to high temperature incendiaries. Sure, only she can do the science after claiming it was impossible. :rolleyes:
In reality samples were obtained soon and no evidence of high temperature incendiaries was found, IIUC truthers then go for exotic things like nano-termite forgetting the cost and difficulty on making plenty of the stuff and that the deployment of that material would still be impossible to miss by many.
http://www.911myths.com/index.php/Recycled_Steel
Sad to say, but what we have here is another example of a scientist that in their latter years think that they can jump to other disciplines at the drop of a hat.
What we have here is another example of why you should check your sources, and in the era of Google it is really irresponsible not to do some checking on where the information comes from and if active experts in the field are the ones being cited.