Kvip is a utility that converts video files from various formats to a video file that is playable on the iPhone and iPod video (5G/5.5G/6G).
Download Kvip from here. Save the file to your desktop.
Double click the downloaded zip file (release016.zip) on your desktop to open it in Winrar or similar.
Extract the contents of the file to a location of your choice. In this example I am extracting the files to a folder called kvip on the Desktop.
Open the kvip folder you extracted and double click kvip.exe.
A windows will open asking you to select the file you would like to convert. Do this then click the Open button.
Kvip will then begin to convert your selected video file.
Once finished a dialog will appear and let you know the name and location of your newly converted video file.
Drag the newly created video file into the iTunes window.
Your video file will then be added to the iTunes library.
Connect your iPhone to the computer. iTunes will automatically detect it. Make sure you select the iPhone from the list on the left.
Click to select the Video tab.
Check the Sync Movies checkbox, then check the box next to the movie you just imported into iTunes. Now click the Apply button at the bottom right hand corner to sync your video to the iPhone!