Audible Explosions and a Flash at the Onset of the 'Collapse' of WTC 2 (South Tower) On 9/11.

0:11 - Sound of first explosion (a flash coincides with this explosion which I show later in the video).
0:15 - Sound of second explosion (not quite as loud as the first one. If you cant hear it, try listening with headphones).
0:16 - Man says: "that's the third".

If you watch the full video (posted below) you can hear the man who filmed it saying that he thought he saw and heard another plane hit the tower. So when he says "that's the third", I think what happened is he mistook the sound of one of the explosions, for what he thought was the sound of the impact of a third plane.

Original video (just click and it plays at the right place)
https://youtu.be/DPw9XiJe09E?t=900