exiftool doesn't remove meta data of MP4 (stuff like "Promotion URL" and "Author URL")
Exiftool is great at removing metadata from photos and viewing metadata from others. ffmpeg is must better to use to remove metadata from videos.  A generic "remove all" command would be this. [credit to a guy who once wrote  this on a forum. You sir, are amazing.]

ffmpeg -i in.mov -map_metadata -1 -c:v copy -c:a copy out.mov