Here I've duplicated the effect with an iPhone camera, and the same flashlight as was used in the video:
Now if the optics of the camera were perfect, you'd not see any rays, just a slight glow around the flashlight from the atmospheric scattering.
The rays come for the light bouncing around in the optics, as the Stackexchange article says. But there are a few different ways. In the video you see a six pointed pattern, because the aperture of my camera is a hexagon.
But in the iPhone photo, and the photo in the OP, there's no clear shape, just lots of streaks of light. This is because the iPhone has a fixed shape aperture, a circle. But it's a very small one, so very minor imperfections and specks on the surface essentially change the shape, and you get these rays.
You can also get a "windshield wiper" ray if you smear the lens in a particular direction. Here I wiped my finger down the lens. This creates vertical streaks that seem to be showing up as "ripples" in the rays, but more noticeable it creates a single very bright horizontal ray, basically caused by the light reflecting off the vertical ridges in the smear at right angles.
And for the same reason lights in the windshield get streaked in the opposite direction to your windshield wipers: