Which of the algorithms from here http://iris.usc.edu/Vision-Notes/bibliography/contentsmotion-f.html#Motion%20--%20Feature-Based,%20Long%20Range,%20Motion%20and%20Structure%20Estimates,%20Tracking,%20Surveillance,%20Activities have you coded up?
Of if you already have the body well segmented and just need to get rid of small noise blobs, you can use bwareaopen().
