Here's the link: http://www.comicbookmovie.com/fansites/JoshWildingNewsAndReviews/news/?a=118946
If it is fake someone put a lot of effort into it. I'm on the fence.
On one hand it would be a cool surprise and the voice is muffled enough for them to still cast whoever they want as the actor.
On the other the background is pretty fake looking (look at the sky and you can see the window washer casting a shadow). Also everything is pretty blurry (even taking the camera credits into account).
I'm leaning fake but who knows...
It is so incredibly fake, evidenced if only by the face that it is still up on YouTube.