Just because the guy states it's forensic acoustic proof of second shooter doesn't mean it's a fact. He makes an amateur analysis from crappy cell phone recordings in the middle of the kill zone, with all the reverberations, echos, impact sounds and amplification through the sound system microphones and it's proof? I doubt it!
Not one person has come out and said they heard shots from any other location other than the main tower at Mandalay Bay. There are many recordings confirming shots from the Mandalay and none of them indicate a second shooter at that location.