I kind of feel like this is a hoax.
1. Nintendo would have said something about this a while ago. It doesn't seem like something they would announce last minute because they want people to know they actually added stuff to the game.
2. The man in the video said there is no release date planned as of now, but I'm pretty sure they announced it was coming June 7th.
3. This could just be some random guy who went to a 3DS event with a Nintendo shirt on.
4. This is not really a formal way of announcing something as big as this.
5. I don't think anyone knows this guy, and he's probably some creepy pedo.
Chances are that it is real, but just some possible flaws.
Edit:
Oh, I didn't read the original post. I read the news on another site so I didn't know that people actually knew this "David Young" so that eliminates 3 and 5. But he probably is a pedo.
Edit#2:
Nah, forget what I said. I could disprove every point I gave. It's legit.