This is a real phenomenon, but it happens rarely and only on very cold days. I’ve seen this with my own eyes, but it wasn’t this colourful. I wouldn’t be surprised if someone cranked up the contrast in post.
But speaking of northern lights: there is a wide range of how bright and colourful they are, based on all sorts of atmospheric conditions I’m not qualified to explain. But I’ve seen some extremely bright auroras and some that were barely visible. You probably just saw a very weak example.
When the conditions are right, the northern lights can take your breath away.