Hi doma,
I've never seen the middle of the three videos before. You are right that the fireball resolves to smoke much more quickly in the latter.
But you see hints of a huge fireball just before all of the cameras lose sight of the explosion for 3 seconds or so.
I was also thinking about the shapes of the mushroom cloud afterwards. There's a different video from West showing this. http://www.youtube.com/watch?v=ja9LF9k2Rjw&feature=youtu.be
How about a comparison with an explosion of what looks like a petrol station in South Korea; http://www.youtube.com/watch?v=rLSl8BtM_2M