The iPhone shoots pictures and videos with its camera, and plays music and video files. The iPhone's built-in software plays videos stored in the H264, M4V, MP4 and MOV formats, such as TV shows and movies that you can download from Apple's iTunes Store. You might have video files saved in the AVI format on your computer, such as a 4.4-gigabyte, 90-minute movie from a DVD that is compressed to a 700-megabyte AVI file. You can view AVI files on your iPhone by using an AVI-playing app that you download from the iTunes Store.
1 Plug one end of your iPhone's data cable into the phone, and the other end into the USB port on your computer. If iTunes isn't running and doesn't automatically start up after you connect the iPhone to your computer, double-click on the iTunes shortcut to launch it. If you don't already have an iTunes Store account, sign up for one (see Resources) so you can download apps. You can also click on the "iTunes" link on your iPhone to search for and download apps, but you will still need to plug your iPhone into your computer to transfer AVI files to the phone.
2 Type the name of an AVI-playing app in the iTunes search box and hit the "Enter" key. For example, type "OPlayer Lite" or "VLC Media Player," which are both free (see Resources). There is also a paid version of OPlayer, and another app called CineXPlayer that requires payment. Find other AVI-playing applications by searching for "AVI" or "movie" in the search box. Click on the name of the app to read more about it.
3 Read the description of the app, verify that your iPhone's operating system supports it, and then click on "Free App" or "Buy App" to download it to your computer. Click on the icon of your iPhone in the left pane of iTunes, and then click "Sync" to copy the app to your iPhone if you don't have it set to automatically sync new apps.
4 Click on the "Apps" tab at the top of the iTunes window. Click on the name of the app that you copied to your phone, such as "VLC," in the section under "Apps." The "Documents" window next to the "Apps" window will switch to display documents for the app you chose, such as "VLC Documents."
5 Drag an AVI video file from a folder on your computer into the video playing app documents window in iTunes. It will start copying to your iPhone.
6 Click on the icon for the AVI-playing app on your iPhone. Depending on what app you downloaded, your documents may appear in the main screen of the app, or you might have to click on something like "My Documents" first to see the list of AVI movies. Tap on the name of the movie you want to watch, and it will start playing on your iPhone.