...and I am struck by the appearance of the tail anticollision light as the aircraft rotates..
The light is not omni-directional, don't assume it's a point source shining equally in all directions. And therefore as the aircraft rotates and pitches etc the light might be blocked on that observational angle by parts of the aircraft, or it just might not shine in a particular direction by design. It's very difficult to drawn any conclusions from the light.