This image may also be of interest - from a while back on the Gen1 Fly6.
What it shows is a vehicle that is passing safely (thank you) and is 'relatively' far away. A bad driver will be closer. There are 9 frames which I cut to demonstrate how you can look through the individual frames to help identify the numberplate. Also by scrubbing and moving the play-head back and forth on the video, the human eye can also help decipher the characters. Closer it is easier - but affected by the light conditions.
I am experienced with digital editing so can also put screengrabs into editing programs and adjust details such as contrast and sharpness as well as a few other tricks. If you get stuck identifying the numberplate - getting an expert onboard with their CSI skills can help get you closer to identifying a vehicle.
With regard to calling the numberplate, it is a great idea that I think is actually worth practising because in the heat of a near miss, it is easy not to do this.