IMO the video doesnt proof anything.
Only that he is a real person.
There are still too many coincidences.
Even if in the end it shouldnt be a Silent Hill game, I will still take a look at Abondend.
Edit: Why are they/he only posting in the middle of the night?
IMO Actors can lie about being Actors or random people hired by Hideo Kojima can also say they're not an actor and be telling the truth.
I think this could just be a guy called Hasan Kharaman, he could work for a Studio called Blue Box Game Studios, but that could be one desk in an office in the Netherlands, but Hasan isn't really there.
Seems strange these guys didn't just reveal the game already, the trailer shown has been stated by Hasan's Twitter to have nothing to do with the game and Abandoned isn't even the real name of the title.
The delay seems like a stalling tactic, to keep the ruse going.
It's very odd that we haven't seen any more of the team, that they haven't got anything on their website and they haven't shown anything of the actual studio developing the game.
Very weird situation indeed IMO.