People who are not reading the full thread are introducing dead ends. The speculation about the little flash before the big one is counterproductive- a proper read will bring up the fact the undercarriage appears to have gone through a low wall on the boundary of the airfield. This will have had a serious affect on the structure and would produce some sort of small explosion at that speed. It is fits with the timescale before the big flash. I do not believe there is likely to be any connection with surges- this is a very stable engine. It is obvious the cause of the accident occurred long before the aircraft even entered the video coverage. The tyre tread question is also irrelevant. Airliner tyres do not have any form of 'tread' to assist with braking. Apart from longitudinal channels, there is no cross tread.