I watched the zeitgeist movie and had issues posting my comment on Hulu. so I hit the cyber highway in search of a new home for my creation. So, those are the circumstances, this is the result.

You know the light bulbs with a little wire in them? When the current exceeds the tolerance of that wire, it fails and breaks. Steel beams are big fat metal wires that have an electrical tolerance that when exceeded, produce sufficient heat to liquefy steel. That's how welding works. The massive buildings had massive power demands, and a live wire can heat up material to enormous temperatures. It's so obvious it pains me to see these people convinced that their on to something. It was religious extremists! I understand that people are capable of justifying madness through religion; however I also understand that the psychosis of individuals that examined the available evidence and posit that it was insufficient and requires disclosure of information that was purposely hidden to prevent the "truth" from being known is in the same self-imposed delusionary category of self-reinforced certainty that is witnessed in people who commit their assertions as certain on the basis of faith. These are honest, caring people who have there relatively peaceful existence suddenly and traumatically broken by a collectively observed or encountered or experienced tragedy. Just like it seems that almost nothing will convince a religious individual that there belief is, I'll say this nicely, inconsistent with aspects of what conventional evidence demonstrates, so to do these individuals find themselves reacting in a very human manner to the sudden implication that their is something more out there beyond the scope of what they where aware of; something which can explain what occurred prior to the event. An event which resulted in them becoming aware of there having been circumstances that were completely unknown to them up to that point, and instilling an innate desire to know what those circumstances were. Due to the disturbing events that caused this effect, they are finding the discovery of what they were not aware of does not have the level of intensity and life distorting surrealistic disillusion that they associated with the feeling they had when the event occurred, the result of which leaves these struggling individuals with the sense that the desire for justice, vengeance, purpose, and closure were never alleviated. As a result any gaps in the resulting explanation can create an emotional and a psychological disposition potentially generating suspicion. This leaves these perceived gaps as focal points for the expression of this unrelenting despondent reaction, in which the hope of filling them results in the these gaps being subjected to homogeneous confabulation by the collective of distraught contemporaries mutually grieving the egregious disaster, desperately trying to fill the gaps in an attempt to reconcile their unfulfilled resolution. A grief to which many of us sympathize, and patiently console the disparity while the afflicted pursue consolation that they may someday learn to accept, subtly relieving them of the consequences of their disconcerting trepidations. -J.

Overall I thought the quality of this production was rather poor.  I watch both conspiracy and debunking videos. 

It is important to remember that conspiracies do happen.  And, the U.S. government has been behind some of them.  The Gulf of Tonkin is one verifiable incident.  A more frightening example of the lengths our government will go to in order to further an agenda can be found in Operation Northwoods.  It proposed the staging disasters in which American lives would be sacrificed in order to justify war with Cuba.  Thankfully, President Kennedy rejected the plan.  But, the plan was conceived at a very high level by military men and shows that nothing is off limits.

Finally, one aspect of many consipiracy theories regarding 9/11 centers around World Trade Center Building 7.  No airplane hit this building.  Apparently it collapsed due to debris from the twin towers.  Some fires were started from the debris in WTC7.  It is possible that the twin towers fell due to the impact of the planes and the resulting fires from burning jet fuel, but none of that factors into WTC7 collapse.  Why was this not covered in a "debunking" video such as this Nat Geo production?

Just finished watching the "projectile" experiment.  My initial thought was: Why not include wings and the accompanying engines?  An 757 engine weighs about 6,500lbs.  If the cylindrical aluminum frame of the airplane can cause extensive damage, why wouldn't the airplane wings which are made of the same material also cause similar damage?  You might say the shape of the wings differs from the point of the plane, but then why wouldn't the heavy plane engines cause damage?  shouldn't they have shot through the pentagon walls, much like the point of the plane?  they are certainly made of more dense material than the fragile aluminum point of the plane..

Two experiments were conducted testing the strength of steel.  One experiment used jet fuel, while the other used thermite. 
 

Unlike the jet fuel experiment, the thermite experiment did not include weights placed on the steel column.  In addition, the thermite experiment seemed to be conducted in a haphazard manner.  The experimenters crudely placed some thermite around the steel column and set it on fire.  I have a feeling that if you doused a steel column with jet fuel and lit it on fire, the steel wouldn't melt either.

It almost appears as though the experimenters had desired results in mind, and designed the experiments to reflect their presupposed conclusions.  If thermite was used in the twin towers, it certainly was not applied in the same manner as the experiment in this show.
 

The narrator mentions that thermite burns at a higher temperature than jet fuel.  If applied correctly it there is no reason why thermite couldn't melt or weaken steel.  However, the experiments in the show appear to contradict this simple scientific fact.  The reason: the experiments were conducted in a very unscientific manner.

Just finished watching the 1st experiment conducted in the video.

One question struck me: Why not conduct an experiment that the "truthers" agree (beforehand) is sufficient to test the hypothesis that fires burning within the towers were the cause of the collapse? 

If everyone agrees that the test is scientifically sound and a proper re-creation of the unfortunate events of 9/11 then the results would be less controversial..

Personally, I would like to see a re-creation of the towers tested.  Use the exact same materials (fire-proofed steel) and architectural designs.  Use a model plane.  Basically, re-create the scenario exactly as it happened (or as close as possible).

Very imformative, educational & factfull. I hope good chage happn to our USA.