I found some pretty amazing footage of Jennings' game winning td against the Broncos 2 years ago. Due to me yelling and the loud cheering by the fans on tv, I didn't notice at the time; but Greg actually broke the sound barrier on that play.
Thanks to a high speed camera, and brand new audio footage of the play, you can clearly see/hear that he indeed has done what no other human has done.
The vapor cone you see in the snapshot, is caused by rapid condensation of water vapor due to a sonic shock produced at sub-sonic speed.
Click to watch!