[chimera]

At that altitude, its hard to imagine the control surfaces being all that effective. It'd have to be thruster activity. Failure of control thrusters is not unheard of. Gemini 8 had to be brought down early because of a stuck-open thruster. In May of 1968, LLRV no. 1 (LLRV was the predecessor to the more advanced LLTV) crashed while being piloted by Neil Armstrong. The failure was in a bank of control thrusters. Armstrong bailed out and lived to fly another day, this time a bit further and with more success.

When this happened my initial thought was a control system problem. It doesn't take much at those speeds to lose control. Loss of yaw control would put it into a spin. From that one video there seemed to be a violent yaw 90 deg. to the flight path. Whether that was a sympton or cause, we don't know.

[Ditto]

Gemini 8 had to be brought down early because of a stuck-open thruster. In May of 1968, LLRV no. 1 (LLRV was the predecessor to the more advanced LLTV) crashed while being piloted by Neil Armstrong.

If I recall correctly, Armstrong was also the pilot on Gemini 8 who pulled the capsule out of a rapid roll from the stuck thruster only seconds before he would have lost consciousness. He was one hell of a pilot.

[RightWhale]

Gemini 8 had to be brought down early because of a stuck-open thruster.

They nearly lost that one. The pilots were close to blacking out as the capsule spun up to one revolution per second.

[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.

[El Gato]

At that altitude, its hard to imagine the control surfaces being all that effective.

Not when you're going on the order of Mach 18 or so, you get plenty of control force from the control surfaces. The fact that the RCS (thrusters) kicked in is what is unusual.