Downloading and playing AVI files on an iPhone requires third-party tools because iOS does not natively support the AVI format. You can either use a universal media player to watch them directly or convert them to a compatible format like MP4 or MOV.
This is the easiest way to watch AVI files without changing the file format. How to Put AVI Files on iPhone or iPad - wikiHow kak skachat avi fail na iphone
Method 1: Using a Third-Party Media Player (Direct Playback) Downloading and playing AVI files on an iPhone