I originally posted this as a comment below the first article. However, I have substantial reason to believe I am right...(and no, ArenaNet you do not have a leak. I just have a highly imaginative, but very likely accurate idea of your plans. I was recently on a fourteen hour roadtrip, so I had some time on my hands to speculate.)
1. I've changed my mind. The trailer will be released and played the first time we as players have access to the game, aka the 25th for most of us.
2. Second, part of the CGI trailer will be Eir swimming discovering an elder dragon exactly reminiscent of the coincidental concept art I chose for the first article. I'm very certain of this.