Yes, that's lens flare.

* It only shows when the meteor is close to the center of the lens.

* You can see reflections of two lens elements, one is smaller and brighter than the other. The smaller one is the element closer to the imaging sensor, and moves in parallax to the other one.

Actually, in that video, you're right, that's lens flare. Still, the superheated trail suggests that something very intense happened at that moment. It could have been the meteor breaking up, but that kind of "burning air" phenomenon is also associated with nuclear detonations.

Yeah, but it's present in other videos too, and moves in an arc, which countersuggests a lens or CCD bucket overflow artefact.