Rogers scored twice as Villa defeated United 2-1 to go third on the Premier League table.
Emery said: “I did it (flung his jacket) because I was not happy with how Morgan Rogers was performing. He scored a fantastic goal but we needed more.
“The second half he was doing that. He started more aggressive and he scored a second goal because he was aggressive for the second action, anticipating and scoring the second goal. It was my adrenaline there for this issue.”
On the home support, Emery also said: "Our fortress and the supporters are very important, how they are transmitting their energy, how we are as well transmitting them our wishes to win, our wishes to play, giving them as well our individual skill, our individual character or courage.
“Of course, how we are feeling here is really fantastic. Myself, I am so proud when the players are responding like they are. After a poor start, how we are now, of course, is something we can feel happy about."