I'm going to talk about video games with my son and his teammates during practice even though the coach told them not to talk about video games.
Why do you want to talk about a banned topic?
I want to spend some time with my son and I'm bored during their practice.
It is good to want to talk to your son, but if the team agreed to not talk about a certain topic, you should respect that. He could get in trouble with his coach.
I don't care
You should respect the team's rule to not talk about video games during practice. You can talk with him about games when you get home. Have you considered taking him to an arcade?