Motion Science shows how you can make film dust and scratches with one effect in Ae.
There are lots of plugins and effects out there that let you easily create the classic film dust and scratches you would see in an old filmstrip. You can also make your own, and it’s surprisingly easy. Check out this new tutorial from Motion Science (Cameron Pierron) that shows how to use Fractal Noise to create the effect.
The fractal noise is one of the most beneficial effects not only in Ae, but in computer graphics in general. It allows you to create the building blocks for larger, more intricate effects. From fire, smoke, and water, Fractal noise is much more than an animated texture. It is a way to create a wide range of visual effects procedurally.