LosslessCut makes it very easy to cut out a section of video. It can also arrange sequences of cuts. It is very fast because it does not reformat the data; that also means it doesn't degrade the quality.
It only reliably cuts at video keyframes; this could be an issue if you want 100% precision on your cuts. It does not attempt other editing tasks such as reformat or region crop.
Like many video editors it is a GUI to ffmpeg. You can see the ffmpeg commands generated and use them outside LosslessCut if necessary.