Mac:
QuickTime Player
Apple’s default media player actually includes a number of great options for making your videos smaller. The only drawback to it is that you can't use it on any other operating systems.
To make a video smaller with QuickTime, open the app from your Applications folder and click File > Open File to load your video.
To begin making your video smaller, click File > Export As. Unfortunately, QuickTime doesn't give you as many options as some other apps. You’ll see 4k (if applicable), 1080p, 720p, and 480p options.
PC:
There are many affordable applications to enable you to compress various video files and reduce video file size. Here are a few we suggest: