"Es" does not mean "this" and "it" in English does not necessarily mean "this" either. "This" says the proximity of the coat is close, probably in sight or hand of the person speaking. With "it" we have no idea where the coat is. He could have left the coat in China and he is now on the other side of the world still refusing to accept that he will likely never see that coat again. But it is Valentine's day so I'm hopeful this guy will get reunited with his coat.
The question I got said "Write this in Spanish" and then when I typed "Es mi abrigo" it wanted it in English