The AVI file might have some metadata in it (movie name, directors etc.), which VLC uses. But if the metadata is incorrect (like whitespace chars), then VLC might not display anything. If some AVI files display title and others don't, I would guess it is related to this.
http://s002.radikal.ru/i200/1008/04/9dda791e9afd.png
At least in here AVI filename is displayed at start (I tested with one AVI).