[Dan Day]

From that one video there seemed to be a violent yaw 90 deg. to the flight path.

That one video didn't show the shuttle sideways, as many assumed, it showed the shape of the camera aperture during an out-of-focus period. Your other points are good, though.

[chimera]

Yes, I saw that explanation, and the initial portion of the video where the image looks like a diamond shape, I can understand the aperature distortion argument. But when it snaps back into focus, just for an instant, the diamond shape disappears and I think you can see a moderately distinct image of the orbiter, it appears like its pointed away from the camera, away from the line-of-flight, and you can see a rear-on view of the main engine fairings. The next instant the whole thing goes away in a kind of flare, which I took to be the initial melting/burnup of the fuselage.

It may be an optical illusion, or a trick of the camera in seeing an apparent yawing movement perpendicular to the line of flight, I don't know. But that coupled with the initial speculation (just that) of a control system problem makes me think he got out of alignment in yaw, then went into a spin. Once the less-protected portions of the fuselage were exposed to the friction, it'd be done for. They did see that thermal anomoly along the one side. Again, does that reflect the root cause or a further symptom of an earlier problem...?