It rather looks to me as though the aircraft is changing size erratically between some of the frames. That wouldn't happen in a continuous set taken from a frame burst .
But it could happen if someone had stitched together a set of shots from frame bursts of separate manoeuvres from the same display, carefully chosen to portray the attitudes displayed in a barrel roll.
That could account for the convincing and consistent lighting and specular reflections.
Just a thought.