An analysis of those flashes may be complicated by multi-layered glass clad polycarbonate windows. There are likely multiple glass and polycarbonate layers producing both refractive and reflective effects not seen with normal windows:
"Although Jim has no special knowledge of what ballistic transparency might be in use at the White House, he’s uniquely qualified to make an educated guess. While Level 4 ballistic glass would stop shots like those fired by Ortega-Hernandez, Jim doubts that’s what is reinforcing the White House windows. After all, the history of attacks on the White House has been one of shooters with powerful firearms firing from a much closer range. At least one would-be assassin aimed a small airplane at the Presidential bed chamber–a security risk that calls for a level of impact-resistance not available with many Level 4 ballistic transparencies.
Asked to guess, Jim hazarded: “That’s probably a Level 8 glass-clad polycarbonate. That wouldn’t surprise me at all–but it wouldn’t surprise me if they had something even tougher that we’ve never seen. I have no idea, but the federal government has a lot more money than most of my customers do.”
https://www.tssbulletproof.com/blog/ballistic-glass-white-house/