Well, Guest Ed, here's a quote from your link:

"Aluminum has a melting point of 660*C, depending on the alloy, and jet fuel burns at 980*C. With the vast amount of debris from the aircraft in the north-east corner (80% of which was aluminum – about 64,000kg), it's most likely that the molten material seen flowing from the building is molten aluminium. Truthers believe however, that molten aluminium is a silvery colour, like mercury, and does not glow orange.

To debunk this one, simply run a Google image search for 'molten aluminum'. The results shows multiple images of the stuff, glowing an orange-ish colour. The search even brings up a diagram, showing the colour of aluminium at different temperatures. What's interesting is that at 980*C (the temperature at which jet fuel burns), aluminium glows light orange, just as shown in the video."

That is NOT inconsistent with the hypothesis presented by the two engineers in last night's programme!