As "open" as DARPA is they are subject to confidentiality and are only allowed to disclose what the DoD allows them to disclose. I am no conspiracy theorist but compare the shape/light of the aircraft in my video to the artist night time rendition from the OP article. Even if the aircraft in my video is different, I can tell you I have never seen anything anywhere near as fast as the aircraft in my video including F-15's, F-16's, F-18's or the space shuttle when it lands (which breaks the sound barrier at very low altitude).