That video is centered on the two towers because, from where the cameraman was situated, if he centered on the burning tower the entire left side of the frame would've been filled with the nondescript brown building in the foreground. As it is the nondescript building is still in the frame but is as unobtrusive as it could be but it still takes up some of the video.
The aluminum airplane doesn't go through the building, it went into the building because of the mass of the fuel it was carrying. That mass was dispersed in the collision. The only things of note that went through the building was an engine, some of the landing gear and some of the now aerosolized fuel.
Here's a simple experiment for you. Get two 12 oz cans of of your beverage of choice. Take an unopened one and throw it as hard as you can at a galvanized metal garbage can. Note the damage to the garbage can. Now empty the second can of its fluid and throw that empty beverage container at the same garbage can as hard as you did the first one. Are the two damage results the same?