Philbky,
You are over-analysing things too much. The video footage was obviously taken immediately after the crash; do you seriously think the police and authorities would allow strangers to get anywhere near the plane - let alone walk around INSIDE it - to take pictures and video footage?
The whole area would be sealed off - even now - and guarded by police.
There were no people from the emergency services in the video, the person in orange was wearing a T-shirt.
You have no idea how people react in trauma. People can often seem very calm because they are stunned. In the video you can see lots of passengers in the distance just standing around in shock: that's natural.
Why do people have to make up conspiracy theories? For what?
I dare say the passenger who recorded it was as shocked as everyone else. And the fact of the matter is the plane crashed, NO-ONE at this stage knows why - not even the air accident investigation team.
More than likely when they discover what actually happened it will turn out to be some simple error/fault which had tragic consequences. Nearly every plane crash turns out to have been caused by something bordering on trivial which leads to a catalogue of confusion or events.