The only scientific analysis of ball lightning that I found was a chance encounter with it in China where they managed to do a spectral analysis. In that case, the ball lightning seemed to be a result of a regular lightning bolt vaporizing silicon. Or they could have faked the whole thing, I literally see one single scientific paper on it. It looks to me like whatever is shown in this video is disjoint from the lightning behind it. The lightning seems to be about 4000 feet away from the camera (there is a big flash at 0:04 and the corresponding thunder at 0:08), where the trees like like a few hundred feet at the most. I think it may also be a bug. Fireflies like the time right before a thunderstorm and are often out at dusk.