Tracers Rounds (From SimHQ)

[Erkki]

A camera's shutter speed is from 1/100 up to 1/2500-3000 in daylight. Animations start working for a human eye after 1/25.

edit: afaik the tracers appear white in guncams(colour ones...) because especially old films are very sensitive to IR light. The tracers simply burn through.

You can find some US kamikaze-footage taken in the dawn/sunset and even night, you can see the full spectrum of the tracers in them. I thought both sides used mainly red, like in il2, for rifle cal rounds.