While it works after dark, the “smearing” of light trails doesn’t work in the daytime due to the iPhone lens not being able to stay open for any significant length of time. Even with the ISO set as low as possible a “slow shutter” (it’s all electronic, obviously) allows too much light in and the video ends up washed out. So the jittery motion that you see in the trails of the cars, there doesn’t seem to be any way to prevent that or make it any smoother. 😒