The Reds twice came from behind on Tuesday as Craig Westcarr and Luke Shiels dragged Alfreton from 1-0 and 2-1 down.
Tom Platt then hit an 88th minute winner to stun the hosts and extend the Reds unbeaten run to three games.
McDermott told the club`s press officer Amar Sharma: "I was over the moon with the result, I'd take three points away from home and the point we got at Nuneaton now looks a big point and a good point for us after the result at Leamington. Three points are important if we back it up and it was good for us to respond from Nuneaton Town.
"I was disappointed with the first half, I thought defensively as a unit we need to stop giving balls away. It doesn't matter who we play. In this league if we give two goals away, away from home it's going to be hard. It was another set piece where they get the free header and they've peeled off us and put it in.
"We're a big team and we need to work on our set pieces and we will work on it. If we can keep clean sheets then we will win a lot of matches and I asked the lads who have been in promotion campaigns and title winning seasons that keeping clean sheets was a massive part of that? Of course, it was. If we are going to be successful we have to keep clean sheets."
McDermott was pleased with how the Reds showed spirit and fight to twice come from behind: "We've showed excellent character, to come back twice from it away from home. The way we played, we didn't suck ourselves into long ball and trying to get the seconds, we kept our shape and when Craig Disley came on; credit to him he got the game by the scruff of the neck and kept us playing, switching the play and stretching them.
"We've caused them problems throughout and I felt we bossed the second half, the threat they had in the second period was exactly the same as the first. We had to make sure we learnt from the first half and we did, Chris didn't have many saves to make and neither did their keeper. But I'm happy that the ball was in their third of the pitch more than ours."
Gainsborough arrive at the Impact Arena tomorrow and McDermott was wary of the Trinity threat: "We take on Gainsborough next at our patch, they score goals, we need to make sure we tighten up. We will always get goals, we have players in this team that can create and we need to make sure our concentration is there.
"We need to make sure our fans get a performance out of us tomorrow, I thought they were brilliant at Leamington and brilliant at Nuneaton, very vocal and they can see what we are trying to do and the we all appreciate the support. If we can make it noisy and get the Impact noisy, this team will kick on.
"They will make it very difficult for us and we will make it difficult for them, they are a great club with great staff and I want us to play and create. We are in a good place and very happy, we move on to tomorrow now".