What you're seeing in the video is the effects of "gain". Basically if there's insufficient light to form a picture, the camera electronically amplifies the signal from the sensor to enable it to be strong enough to be processable and show something meaningful. Unfortunately with electronics, you also get transients (small unwanted electric currents in the back ground), and these signals get amplified as well which is why you see speckling and grain.
That's the technical side. The non technical side, is the streets look very dark even with street lighting and I'm unsure how sensitive the A119 is. One way to try to alleviate the issues as Jokin said above, is reduce the frame rate to 30fps. With 30fps, each frame is exposed for longer so whilst you get more slightly blur with movement, you get more light so a brighter picture.
The other issue is check the memory card speed and make sure it's fast enough. Ideally you want at least a Class 10, and there's some argument for UHS-1 minimum with HD video, depending on the compression levels used by the camera.
If you really can't make the A119 work, then consider swapping it for a WR1 as mine makes an excellent job of low light as you can see in the 2nd "performance" video here:
https://dashcamtalk.com/forum/threa...ighting-weather-conditions-comparisons.30018/
Just be aware, all cameras struggle in really low / no light (especially as there are no headlights to the rear), it's just some struggle more than others.
