I was wondering if they were showing DG's warping movements to take us back to the last boss fight in SAO...
My guess is that DG is an admin or whatever haxor profile. Since the company running GGO is in the US and nobody knows shit about it, it might be DG is in fact one of the founders/developers or whatever position that granted him access to the source code or whatever hack needed for his deeds.
That gives him access to any player's identity etc...