Thanks for the video. It does appear to show the appearance of debris from the break up. This debris return lasts for 5 minutes, during which time it would have been falling to earth. That's 5 mins to fall 33000 ft.. Seems reasonable. Although the debris is still there when the video ends - so it could have taken longer than 5 mins.
At no point could I detect the existence of any military fighter aircraft in the vicinity, either on PRI or SSR.
Apart from the break up & disappearance of the B772, this does not present any evidence of an aircraft which may have shot the B772 down. Nor of the actual missile.