Well you're aboviously doing them a hell of alot heavier than i was, but i keep the albow angle less acute than that and there is hardly any movement at my elbow joint similar to this:
http://www.exrx.net/WeightExercises/...nal/DBFly.html
Am i doing them wrong? Yours look more like what my dumb bell presses look like, i guess it's something to do with the outward rotation in the motion that makes it a fly is it? They look like they're doing their job whatever they are!