*Sigh*
Could a missile have been fired from a plane hitting the south tower? I don't know the answer to that.
Are we talking hypothetical scenarios? Then yes, certainly a missile could be fired from a plane and hit a building. The Air force does it often.
Or are you asking if it happened on 911? Then the answer is no. Missiles of a size that makes any serious damage to buildings are fairly large, noticeable, and noisy.
The first one the most interesting part is at about the 3 second mark and is circled. Not sure what that could be. Also towards the end he shows what could be secondary explosions.
http://www.youtube.com/watch?v=wc4wsjKbYTQ&feature=related
First item is a short flash, either behind one engine or on the face of the building.
It could be:
1) A video artefact.
2) Something from the North Tower or other debris tumbling in the air much closer to the camera.
3) A flash from the engine (after ingesting something floating in the air; the air was full of debris, and birds are also observed on some videos).
4) Someone taking a picture of the approaching plane from the tower.
Since it is not noticeable in videos from other angles, the best guesses are #1 or #2.
Second item are explosions. I'll tell you something: When a fuelled airliner hits a large structure at cruise-speed, there will be explosions. Plenty. It would be far more strange if there were no explosions.
The second video...the most interesting parts starts at around 23 seconds. It definitely looks like something is racing along the plane and than smashes into the building just before the plane.
http://www.youtube.com/watch?v=-x8fs2sZmas&feature=related
With this poor resolution, it makes absolutely no sense to look for details. I don't see anything out of the ordinary, but what you see could be light reflexes, JPEG artefacts, pixellation artefacts, normal shadows looking strange due to low resolution. A good rule of thumb is, if you start seeing pixels, zoom out. Otherwise, all bets are off.
These videos taken together are awfully interesting. I'm not saying that it is a missile, simply saying I don't know. I've looked and looked and can not find a better reason for this.
There is no sign of missiles in these or any other videos from that event. There are also no eye witness accounts that indicate missiles were fired.
There were no sounds indicating missiles.
There is no sensible reason to suspect missiles were fired, there would be no need to fire missiles.
No missiles.
Hans