Another bit of information came to today....re the Rotor sounds on the audio.
The Main Rotor emits a N/Rev 4P 17.6hz sound but the tail rotor emits a slightly higher pulse of 21hz causing a problem telling the difference between them by ear. I am assuming that is during "normal operation" with standard Nr set by the Crew.
As poor as the one video is it can still provide a lot of information when examined by the investigators.