1. Open the MPEG Streamclip application. It is in the main Application folder or you can search for it using Spotlight.
2. From the File menu, select File>Open Files….. Choose and open the video file you want to convert.
3. From the File menu you will have several export options. A good standard file format is MPEG-4. It is compressed and works well for internet sharing and platform compatibility.
Select your Export option.
4. In the Exporter window that pops up, choose your preferences. If you are unsure, use the defaults. Select Make 'MP4' and your file will be converted to the new format.