To reduce/compress a video size you could use:

ffmpeg -i input.mov -vcodec libx265 -crf 28 output.mp4

Be aware that libx265 is not supported in many players so you can always fallback to H.264:

ffmpeg -i input.mov output.mp4

https://unix.stackexchange.com/questions/28803/how-can-i-reduce-a-videos-size-with-ffmpeg