Your video settings will need to be a trade-off between what quality you want to record vs how much footage you want. You may need to experiment over time to get the recorded quality good enough but still having storage for the right number of days.
No right or wrong answer but personally I set:
Main streams to variable bit rate (5120 max bitrate), highest quality, frame rate and resolution.
Sub streams to variable bit rate (512 max bitrate), medium quality, 10 fps and 640x480 resolution.
The only way I know of to capture reflective plates at night (with an ANPR camera) is to set exposure time to something high like 1/2000 but that means the normal nighttime image looks completely black at night. If you want to capture plates it's always best to have a specific ANPR camera set to 1/2000 or similar. Then your normal camera capturing a normal nighttime image. Of course the ANPR cameras are expensive...
Although I don't know about newer HikVision cameras, perhaps there are fancy settings on some nowadays to help with the reflective plate issue? I don't have many new cameras so don't know...
