Yea I think sad to say that Azeo's comment was spot on, there are quite a few comments saying that the video is indeed an old commercial done by Wizet to promote Maple Story when they initially launch it.
So yea I'm still not sure how to make head or tail about the 3D version of MS. For all we know this could all be some vapourware.
Especially if you consider that KMS just recently release that new set of Knight of Cygnus class, and GMS is anticipating the pirate class.
It would be kinda silly for Nexon to release another game that might zaps the Maple Story fanbase (and $$$ source).
But then again ... I guess we shall wait and see.