That's an easy question. Um, what bout the HUGE airliner that crashed into the building doing 500mph? You all like to forget this fact when it becomes inconvenient, right? Maybe this plane busted open some therma/ite containers...which scattered the therma/ite powder across the building.
The corner we see the therma/ite pouring from in this video:
http://video.google.com/videoplay?docid=545886459853896774
Is on the opposite side from where the plane impacted...so the plane would have pushed any materials in the building i.e. therma/ite over to this side.
Or, as an alternate explanation, the aluminum from the plane settled against this far wall, as did a large quantity of burning jet fuel, providing both the material and the heat to produce molten metal.
Since, as Gravy mentioned, glass has the same melting point as aluminum, and it glows orange when melted, and there was likely a great deal of broken glass as the result of the collision, isn't it possible there was glass in there as well?
The advantage of this explanation is that we KNOW there was fire, we KNOW there was aluminum, and we KNOW there was other material, such as glass, that could have imparted an orange glow to the metal. We DON'T know there was thermite, so it is an unnecessary entity.
Also, look at how this molten material is giving off sparks like a therma/ite reaction. Those sparks and reactions are caused from heat that exceeds temperatures that could have been present on those impact floors. Why? Because, science tells us that certain materials can only burn so hot. Jet fuel, can only burn up to about 1000C, and organic material such as computers, furniture, carpet etc...burn even cooler than that.
Do you have a source for this? It seems to me there are many factors that make a material burn hotter or cooler than it normally does. Did you know that it is possible to melt a charcoal grill by burning charcoal?
You would temperatures in excess of 1000C to make a molten metal spark and react like that. This is another way, I claim I scientifically proved this had to be therma/ite or a therma/ite like substance.
No, to scientifically prove something you have to do more than use big words and claim it is true. Otherwise, I could scientifically prove that monkeys are flying out of my butt, and the word "scientific" would lose all meaning.