i think it is strange that ISIS were video recording the plane. Why? unless they knew something was going to happen to it.
or maybe they have some geeky ISIS members who plane watch at 31,000 feet inbetween the beheading videos they release.
i can see they might be watching for jets but filming a plane..seems strange to me at least.
Another clue: the plane broke up/exploded soon after reaching cruising altitude. This could indicate a barometric-pressure trigger in a covert bomb inside of checked luggage.