The hosts came from a goal behind to beat Sheffield Wednesday 2-1 thanks to Luke Varney's second-half double.
It was Leeds' first win in eight games and took them six points clear of the relegation places with four games to play.
McDermott said: "I was really pleased. It was hard in the first half and we knew we shouldn't have gone in a goal down but there was a good response after the interval, which was really important.
"We needed to pass the ball and create things and I thought the players were really brave in the second half.
"I told them at half-time that the crowd really wanted to get behind them. I've been at places where that hasn't been the case but when we got to 1-1 it made a real difference.
"They were two very well-worked goals. The first was just over the line so I am glad the referee and linesman spotted it and the second was a fantastic bit of skill from Ross McCormack and a really good header by Luke Varney. It was a really big win for us."