You are not "seeing things", although the euphemism is kind of funny considering this is Dead Space we're talking about.
Quip aside, the fur is clearly moving up and down in that video. You're right that it is a minor issue but it does add to the cinematic quality. They clearly intended to do it; rarely does something happen in programming that is an accident *and* beneficial.
I will not be home until late tonight so I may be unable to reproduce this issue tonight. Time is a casualty of having two jobs.
In the meantime, what video card do you have? What video setting do you have the game on?