There are some interesting discussions on the veracity of the video. I'm surprised that no one from government agencies has stated that the video is false. My recollection is that this is usually done.
DIBO provides a good analysis of why the video might be true. And the analysis suggest there may be an initial explosion and then an ignition of fuel. That sequence fits the possibility of an on board explosion and then an explosive ignition of aviation turbine fuel. That sequence fits some of the scenarios that have been put forward on this forum.
ThadBeier has put forward some very solid points on why it might be fake. There are two elements of ThadBeier's ideas I'd like to challenge though. The first is Rayleigh scattering. Rayleigh scattering generally applies to gases not solids. A black smoke plume is a plume of unburnt carbon particulates, not gas. If we can see aircraft and white contrails at those altitudes in colours other than blue, I really don't see why we can't see black carbon at those altitudes, particularly because I don't think Rayleigh scattering applies so much in this instance. The second is in relation to the speed of the plume. The plume does look too slow (just simply comparing it to contrails), however, the aircraft may have rapidly decelerated after the explosion, and would have been losing altitude quickly. So the vector is complex in relation to the camera position. The aircraft may have very quickly moved from fast horizontal flight to a vector which has a slow horizontal component and a vertical component accelerating from +ve (still climbing) to -ve.
It is very normal to see thick black smoke when aircraft fuel catches fire in air. There are any number of reason for the whole of the end of the flight not being taken including such simple mistakes as running out of memory.
I'm not saying it's not a fake, but I don't believe the arguments for it being a fake so far are strong enough.