FFmpeg is a free and open-source video editing tool capable of trimming, cropping, concatenating, muxing, and transcoding almost any type of media file you throw at it.
The following command splits a video file into separate files of a given duration. In this case, we are extracting a video into three separate files, each of 15 seconds:
$ ffmpeg -i input.mp4 -ss 00:00 -t 00:15 part1.mp4 -ss 00:15 -t 00:15 part2.mp4 -ss 00:30 -t 00:15 part3.mp4
Similar to above, we can split a video file at a given point. Here's how to split a video exactly 1 minute from the start, resulting in two separate clips:
$ ffmpeg -i input.mp4 -t 01:00 part1.mp4 -ss 01:00 part2.mp4