I write a lot about structure because it helps gives a shape, whereas many amateur productions flop around because they have no narrative spine or sense. There's more to it than that, obviously, but it's something sadly lacking in most fanfilms.
People in fanfilms talk a lot about character, but few of them that appear are very compelling. So many fanfilms have the characters reacting to the events instead of driving the action, which makes them uncompelling as characters no matter how much dramatic backstory they're given. Who they are isn't interesting. How their character compels them to act or fail to act is what makes them interesting.