Ruben Amorim was heard expression his frustrations at one of his Manchester United players to his staff during their club's 4-4 draw against Bournemouth on Monday evening.
The Red Devils had led three times at Old Trafford, but were ultimately forced to settle for a point following a chaotic match.
It proved another match in which Amorim's side had allowed points to slip away from them at home, following a recent 1-0 defeat to 10-man Everton and conceding late to draw 1-1 with West Ham.
New footage from close to the Manchester United dugout has revealed Amorim's frustrations during the match.