The video is obviously genuine and taken soon after the accident. OK, so making a film on a mobile phone would not be the priority for most of us (I hope), but this guy just survived a plane crash and I'm sure had any residual sense shaken out of him. People act in different ways. Simple as that.
It must have been the most bewilderingly disorientating situation to be put through. I felt nauseous just watching it, let alone what it must be like to be there. The eerie calm captured on tape is surely what you would expect immediately after an accident and before the emergency services arrive. No need for conspiracy theories IMHO.