It might have something resembling that meaning in the Street Fighter community (though, as far as I know, it's still way more general than described in this article), but, for video games in general, it is mostly used to mean "just a bad player."
Scrubs aren't people who don't do cheap moves, scrubs are those who refuse to learn how to beat cheap moves and try to get others to stop doing them. In fact scrubs often do cheap moves and will get angry at you if you perform the counter to his cheap move, calling your counter cheap and instead wanting you to fall for his cheap move. That isn't fun for anyone.
Sounds like scrubs are just complainers. A friend of mine who played soccer told me that the least fun teams to play against were those who would just immediately start complaining to the ref about everything.
Typically used as an insult by someone that just lost to another player that didn't play the way "they should have played".