How about out of your four sentences, only the last one has a shred of truth to it.
Get yourself a copy of "Waco - Rules of Engagement" and watch the FLIR imagery at the end. Then tell me what in Nature will produce flashes of heat that start suddenly, flash at a regular pattern, and then stop suddenly.
I really would like to find an answer that does not involve automatic-weapons fire.
The "sunlight reflecting off debris" answer doesn't work, because sunlight reflecting off debris would look more like reflections off a mirrored disco-ball. I would sleep much better at night.
To reiterate, I really would like to find an answer to that question that doesn't involve "government agents machine-gunning people trying to leave a burning building".
The ball's in your court.
Are you serious? Every one of his sentences were completely true. No, they may not have started the fire, but their actions had those people scared so that they would rather have burned than be shot by the BTAF thugs. Which by the way they did to the first two that tried to escape the flames. So, you tell us where he is misrepresenting.