I think spirits that have crossed over can visit where they like. Ghosts that have been trapped or have chosen not to cross over are often attached to this earth plane for some reason and seem to stay around the area of their concern. Weather they are forced to stay in a location is something I dont think we have a way of knowing. I think the the residuals are just replays of time gone by and not sentient. Of course nobody really knows and its just my own conclusions from what info iv'e taken in from books, and shows.