PAYETTE - Put your wallet back in your pocket. Dan is Not selling this signed JFK Assassination Photo.
Brandt did not come forward until the 1990s. He gave an interview for the Sixth Floor Museum Oral History project, viewable
here.
His recollections are interesting. He said that JFK reacted to the first shot and the first shot occurred after the car had passed by where he was standing. He estimated it was 60-70 feet from where he was standing. He also commented on the reverberation being loud .
If he was standing where he said he was standing, as shown, then he is obviously wrong about the 60-70 feet. We can see JFK reacting when he is no more than a 45 degree angle from the position where man with a hat would have been in looking at Altgens #6. If JFK was 15 feet from the curb then the car had only gone 15 feet past that point when he began reacting to his neck wound.
So it may be that his estimates of time are wrong. Or it may be that his identification of himself is wrong.
Since he is identifying himself from the back, he must have identified himself by the hat. There is only one person seen in that part of the zfilm wearing a hat, so he may have concluded that must be him. But there are at least two other people along Elm St. with similar hats. Altgens #6 shows another man with a hat:

and the early Zfilm frames also show a man who appears to be wearing a similar hat standing just to the east of the lamp post:

It is interesting that he uses his right hand to show the direction he ran to the tree after the second shot.