I'm pretty sure they've included bits and pieces from later in the original game in this trailer, which means the second disc of the remake must be close to completion.
Also, I haven't read up on it yet, but it seems the ghost-like creatures must be visions of the Ancients. That's my interpretation, anyway.
The question remains how fast SquarEnix will be able to come up with the remaining three or four discs of the remake. I do hope we won't have to wait an entire year for the continuation, let's say what happens after you leave Midgar all the way up to the return to Nibelheim.
And I'd love a first announcement for the XBOX version release date, please.