It keeps track of which files you've played (e.g. to automatically pick the next episode in a series), it automatically downloads metadata and cover art so you have a nice browsing interface, it manages multiple profiles so that e.g. you can limit your kids' access to only G and TV-Y or filter out genres a user doesn't like, it lets you set parental controls to limit the amount of time watched in a day (or disable it at certain times of day), etc.