[Izzy Dunne]

The tail is clearly visible tumbling away from the shuttle in the first part of the clip.

It's not so clear to me.
There is an optical artifact - a "ghost" image of the shuttle itself - clearest when the zoom is at maximum.
As the zoom-in is happening, this artifact moves away from the shuttle, because of the zoom effect. This sort of artifact is common in viewing very bright objects.
Once the zoom-in is complete, he artifact is on a constant position, relative to the shuttle.
As the camera zooms back out, the artifact moves closer to the shuttle.
About the midpoint of the clip, the left side of the shuttle (right side of image) takes on a reddish glow, and then (unfortunately) the zoom-out starts. Then the trail gets longer.
But I see no tail-piece coming off.

[Justa]

An artifact? Hardly, it is the size and shape of the tail, which by no coincidence, is not visible on the orbiter. In fact, as it tumbles it comes in and out of view and shows atmospheric distortion. When it is perpendicular to the camera it presents a good image and the black rudder markings are visible in at least one frame. I do not have a video player which can capture frames to .jpg or I would send the applicable frames by e-mail. Is it so difficult to pause and move through the video clip? It took me approx. 30 min.s to find the frame I'm referring to.

I'm confident someone else who has video capture software will soon post the frame. Between the clear frames and the tumbling of the 'artifact' throughout much of the video it's a no-brainer -it's the tail.