The S manuevers used for braking are up to 80-degrees to the orbiter's glide path. I believe the tail broke off during a R-hand S-manuever leaving the shuttle stuck facing south, without the ability to turn back into the glide path -as the video depicts. That would put it's left side facing down the glide path during reentry which the orbiter is not designed for. As it descended the atmosphere destroyed it, from left-to-right. The end of the video clip depicts the beginning of this very thing as the main object is seen to flare-up, i.e., burn. The tail is clearly visible tumbling away from the shuttle in the first part of the clip.
Sad but true.