We all know that fire burns upwards. It is also the case in an aircraft up in the air. This is due to gravity. The hotter (thinner!) air is pulled down by gravity to a lesser extent, compared to the surrounding (thicker) air. The colder air is thus pulled down, while the hotter air of the flame goes up. This is what causes the shape of flames. Fire burns upwards. So, let us look again at the smoking gun: the cargo (below deck) door.
At 2:50s in the video above, a part of the cargo door is shown among the remains. It is the mechanism for opening and closing the cargo door. It shows no damage of fire.
Here is a youtube film about a cargo door (below deck).
And another video from the French Alps where they searched for the plane’s tail.
So somehow, mid air, the cargo door was crashed and sabotaged after which a fire took place, yet only locally. The bottom half of the door frame is clearly blackened, after it was crushed to pieces. This did not happen during the crash cq. on the ground, because the remains around are not blackened. It happened mid air. And somehow this strong fire did not burn upwards. The actuators of the door (top of the door frame) are not blackened!
Again, this evidence supports the theory of a small terrorist team leaving the plane in time, with a most expensive parachute: an ejection cabine.