At first, we need ffmpeg package which could be downloaded from here: https://www.ffmpeg.org/
The sample batch script file (e.g. split-and-merge.cmd) might look like:
REM prepare first video part
ffmpeg -i myvideo.mp4 -codec copy -ss 00:00:10 -to 00:00:20 first-cut.mp4
REM prepare second video part
ffmpeg -i myvideo.mp4 -codec copy -ss 00:00:30.15 -to 00:00:40.00 second-cut.mp4
REM export files names into temporary file:
(echo file first-cut.mp4 & echo file second-cut.mp4)>list.txt
REM and finally, merge them:
ffmpeg -safe 0 -f concat -i list.txt -c copy final-output.mp4
REM lastly, delete temporary file:
del list.txt