a little outside your timestamps
easier for me to do it than teach it, but used these web tools along with Monosnap ap in between the 2.
https://www.y2meta.com/en108 (you will battle popups, but fastest I know of)
https://www.online-convert.com/result#j=63d56c9c-0a18-4c82-8ba5-6977be83b9df (reduce size)
also reduces size:
https://www.xconvert.com/compress-mp4