I do not believe the object in the Arizona home video is the elevon.
I agree with r9etb in
http://www.freerepublic.com/focus/news/835531/posts?page=108#108.
The object may be the left landing gear door.
If the TPS tiles in the vicinity of the left main gear latch were damaged, the heating could melt the latch and the door could swing open.
On the other hand, I think there are indicator lights which alarm if the latch opens or the door is open.
NASA stated 48 hours ago that the orbiter was compensating for increased drag on the port side (which was inducing a roll). If the increased drag on the port side temporarily is reduced at the exact time the AZ video shows separation of the object in the video, then something was torn from the left wing over AZ.
If memory serves, the orbiter landing gear door is designed to drop open quickly in the event of failure of the gear door latch to decouple in the seconds prior to landing.
Plotting wing temperatures on a graphic image of the vehicle is easily possible using PC technology.
I'm sure JSC engineers are working the problem right now.