For the plate raises I think you are getting mostly front delts(shoulders) by doing the entire motion. I think you could also use the exercise to roast your traps by only doing the top half of the movement. I like that you went back to YouTube. DTube always takes forever to buffer at least for me.
Yeah I'm definitely trying to hit those shoulders, just to get them loose and warm for some heavy benching, I think doing that has helped me work through the nagging shoulder pain I'd dealt with before. And I never thought about just doing the top of the range for traps, I'm gonna have to try that. Thanks, Mike!