A few days ago, I watched this video on YouTube:
World Trade Center South Tower Collapse

It shows the white smoke that is coming up from the base of the twin towers.
It also captured the people in the streets and the police helicopter above the north tower. But let’s concentrate on the face of the South Tower, right when it begins to fall. The first flash is visible at 1:24 on the upper floors on the left side of the building. In the following seconds, you will find much more of them, if you look closely. Just focus on the left corner. You can see a couple of little flashes there! You see, all flashes are on the left side and the  South Tower is coming down to the left side.
The desciption of this video says, that it was shown on television worldwide.
I’m sorry if my English is a bit bad. I’m from Germany! ^^