Alleged ISIS video
Quick point re this - the alleged ISIS video shows what appears to be an explosion at the centre fuel tank followed by a trail of black smoke as the plane flies on with the tail still attached (no sign of any large parts detaching from aircraft). The VS section debris on the ground shows no sign of the heavy sooting I would expect if the video were genuine.
I'm still more inclined to it being video game footage filmed from a flat screen tv with a mobile phone - game graphics really are that good these days.