FFmpeg is my swiss army knife for video manipulation. Since there are so many options I find it difficult to remember the syntax. The most common function I use is extracting a clip. So here it is.
ffmpeg -i input.mp4 -ss [hh:mm:ss.x] -t [hh:mm::ss.x] -c copy output.mp4
The first time (-ss) is the start time and the second (-t) is the duration.
Now I won't have to rely on Google or man pages.