Get real, we have a friend that deals strictly with emissions, smoke, dust, etc. He uses extremely sophisticated and sensitive equipment to determine what is in smoke, dust, air, etc. So I know for a fact taking a color chart and holding it up to a photo or a video is as accurate as a .410 shotgun at 1000 meters.You could do a color balance to a known 'reference photo' of the side of the building and see what color you end up with. See the real white smoke in the corner, that is smoke from thermite, that same color of smoke can be seen from the bottom of one of the towers just before collapse.
Youtube, the Wikipedia of videos. Great source ...... for entertainment.