You want "ffmpeg -ss <start time as hh:mm:ss> -t <length in seconds or as hh:mm:ss> -i <your video here>.mp4 -c copy output.mp4" or something along those lines.

I used to use OpenShot. I totally forgot how to use it after a few years hiatus and I could not find a way do what I remember I was doing, so I switched to plain ffmpeg. I use it to cut pieces of videos and extract the audio track. I use Audacity to denoise the audio, adjust the volume and silence some sequences. Then ffmpeg again to assemble everything into the final video. That never crashes and it's easier to document than working in a GUI.

Wow, the police actually care about stuff like that over there? what a world.

It varies a lot between different areas as to how well they deal with it and they have inconsistent standards as to what consists of actionable evidence. I'm covered by Avon & Somerset which is one of the better ones.

Meanwhile here in the states the most significant police action in regard to cyclists rights I can identify is the time I took the lane in front of a police cruiser due to a car illegally parked n the bike lane, pointing at this infraction as I did so, and the pig riding shotgun rolled down his window to mock me as they cruised past.

A good one, right?