As performers most people and myself tend to dramatically move our body around as we play with the music...some pianists do this a bit over the top, do yo think some people actually choreograph their "body movements" on purpose just to show off? hehe!
i dont' think one should worry about "body movements" - some are needed for specific purposes! and if you don't think at all "oh, i should stand still" or "oh, a big body move back and forth wuld look pretty here", then you won't move more than necessary. in music it's very very important that everything is natural - including body movements (imho)
This girl at my school, she's always looking at the ceiling and looknig around the room like she's looking at something. it dosnt look horrible but i always wonder what the hell shes looking at.