It seems I'm not the only gaming channel hit by this guy. It sounds like he posts a video on a game, and then tries to put claims when other people cover the same title after his. Of course, you can't monopolize coverage of a single game, that's not how copyright works. So either he has a very skewed view of copyright, or he's just trying to earn money on other peoples work. Sadly, YouTube seems to support almost anyone who claims copyright on others work, with no need of evidence. And since the only sure way to stop it is to sue the guy, which can be costly and time consuming, it makes small channels easy prey.
Honestly, I'm not that upset about it. I just feel bad for channels taken advantage of this way. I also feel sad for people who think they have to stoop to such levels in life. We have similar size channels and tastes in games, so this is a person who I probably would get along if he chose to reach out to the community rather than exploit it.