ffmpeg -i whatever.mp4 -c copy -an whatever_nosound.mp4

Pretty sure ffmpeg works the same on Windows as on Linux so that should work. Should also be very fast since it's not re-encoding, just copying without the sound. '-an' is the switch that removes the sound.

Done some tests and stripping the audio is unlikely to save much space. This command will reduce the resolution down to 720 and strip the audio and use a pretty low bitrate. Should save some space. Obviously you can reduce the resolution further by changing "1280x720" to whatever you like. You can also change the bitrate by editing "-crf 30" to whatever you like. Higher crf = lower quality. (goes from 0-51 I believe).
 

ffmpeg -i whatever.mkv -an -vcodec libx264 -crf 30 -threads 0 -s 1280x720 whatever_smaller.mkv

Needs a version of ffpmeg with x264 support. I have no idea whether the default one on Windows has this but if not you can download one that does from here: https://ffmpeg.zeranoe.com/builds/ (may as well get the static builds to keep it simple).
 

Thanks babes, I appreciate you too.  I was just getting miffed with how long it seemed to take to upload a relatively small file to dropbox, so thought I could take a minute to save some upload time.  This is definitely turning out to be harder than I thought, so I'll just work on being patient.

<3