Step 1: Load video files
Install and run Mac iPhone Video Converter. Click "File -> Add Video Fiels" button to load video files from hard drive. Or you can drag the files to this program directly.
Step 2: Set an output format and destination folder
Set output format from "Profile" drop down list; then click "Browse" to select the destination folder for converted files if you want to change the default folder.

Step 3: Convert video to iPhone supported format
When preparation finished, click "Start" button to convert videos for iPhone. If you want to merge several videos to one file, just tick "Merge into one file" at the lower right corner.
After finishing converting video to iPhone compatible videos, find and sync them to your iPhone, you can then enjoy any video on your iPhone anywhere and anytime.

Read Guide: How to Convert Video to iPod for Mac?