OK, so it’s a ringer, made for/by an advertising agency. I don’t quite understand why that makes it somehow less awesome than if it had been put together by some other bunch of film makers.
Is realising this sort of thing hard? Yes. Is the execution technically impressive and original, creative, etc? Yes. Does some bunch having been paid to do this detract from the film? No.
Passing it off as a fan film, however: that’s plain wrong. There’s simply no need. It’s cool. We like it. End of story.