I think she just got lucky with catching the exact moment that one or two flash bangs were going off simultaneously. In the video, she says she climbed that tower and was on there for about an hour before the reinforcements came and started to break up the protest. If it had been a real insurrection that was even half-assed organized the capitol police would not have had all that time to react.
She’s a Reuters photog. IMO it wasn’t an accident: she was put in position there and the flash bangs were set partly for the photo op.