Sorry to witness the loss of power and subsequent damage. If it helps in analysing the reason for failure: as soon as the throttle was opened to begin taxying from the parking area I noted two or three "streaks" of blue smoke appeared from the RHS exhaust pipes but it cleared almost immediately.
In retrospect I wish I had found a way of alerting the pilot but how and when stood on the sidelines of an air display does a spectator do that?