"Why WTC 7 went down in the first place?"
He knows what he heard, and he heard explosions.
The guys from Loose change wanted to keep Barry's identity a secret, "until the movie was released", even Alex Jones said he didn't agree with that. But Jason Bermas slipped and said his name, (Barry) on air. This is a powerful interview, and they are not scheduled to release the Final Cut until "late fall, or early winter", we just don't have that much time to sit on this kind of information. Barry Jennings is someone that has the ability to lure other eyewitnesses to the foreground.
Barry Jennings account on 911.