MP4 files can come with a number of different formatting options to help compress video. You may have MP4 files that are simply too large to upload to the Internet to sites like YouTube. Since MPEG-4s (MP4s) are a standard for QuickTime technology, QuickTime Player allows a number of options when compressing and exporting MP4s to achieve smaller file sizes.
Download and install QuickTime Player.
Click "File" and "Open File" to locate your MP4 in the menu window and open the file in QuickTime.
Click "File" and select "Export" to enter the "Save Exported File As" menu. Choose "Movie to MPEG-4" in the "Export" menu bar.
Click "Options." Change your file format (at the top of the "Export Settings" window) to "MP4" instead of "MP4 (ISMA)." This will cut the file size roughly in half.
Change your "Video Format" to "MPEG-4 Basic." Choose your "Image Size" and click "OK."
Rename your file, if desired, and click "Save" to begin the compression. This may take several minutes depending on your file's size.
To compress your MP4 even more, try lowering your data rate from 64KBITS/sec to 32KBITS/sec.
Compressing your MP4 files will result in loss of audio/video quality.