For making your video smaller using QuickTime, launch the app from the Applications folder. Drag your file or click File > Open File for loading your video. Next, click File > Export as, and you’ll see the following options: 4K (wherever applicable), 1080p, 720p, and 480p. Choose from these options and continue to export your file. The new file will be smaller than the original file.
Windows, Linux and Mac allow VLC. Download and install VLC Media Player. On the home screen click 'Add' and then select the video file or files you want to compress. Then click on the ‘Covert/Save’ option to see the options. In the options select ‘Video for YouTube HD’ or ‘Video for MPEG4 1080p TV/device’ for retaining it in the highest quality. Click 'Save' to compress and save the files.