I've tried it, for a gaming channel doesn't seem to work so much no matter the community. + I have no time to get involved with the Google+ gaming communities, they're a bit broader in terms of what people are looking for (e.g. some for pics, vids, chatting etc...), and I also feel spammy just posting to their communities, post and run basically xD I don't want to do that. I've also had too many situations where people have just +1ed the post for no reason, it also seems to attract a lot of non-english speakers (primarily on the bigger communities) which considering I want to build a community on my channel, it won't help much if I can't speak to them haha
But I find it easier to get involved with YouTube communities on YouTube directly as they're there for videos mostly.