Villa fought back from 2-0 down to win 4-2 yesterday.
McDermott said: "I thought we played really, really well in the first half and we were good value for a 2-0 lead.
"Our play was excellent and I am looking forward to watching it again on TV tonight. We could even have had more goals. But if you are going to lose a game that's the way to do it, especially in the FA Cup.
"We came up against a class side and we needed to keep it tight for the first 10 minutes after the break and we just couldn't do that.
"It wasn't nerves. We came up against players who could be in the Champions League next year.
"They have pace, power and quality all over the pitch and I think we gave them as tough a game as they have had all season.
"We knew at half-time that they were capable of producing something and they certainly responded to whatever Martin said."