NOTE: The ideal solution is to shoot with more light – or a larger sensor – or, um, a better lens. You can see it especially clearly in the sky, the side of the red car and the darker parts of the pavement. Notice all the grain (called “noise”) in the image.
Your eye can spot it immediately but, software? Not so much. The problem is that, from a software point of view, it is very hard to tell the difference between noise and texture. Video noise is a common problem in video clips shot in low light or with small sensors, such as cell phones or action cameras like the GoPro. This is specifically designed to quickly reduce video noise – and the results can be quite stunning. New with the 10.4.4 update to Final Cut Pro X is a Noise Reduction filter.