Need a tutorial for iOS to play video files in my application

I am going to build an iOS app that will download video from my web services to play offline in the application.

I am looking for a tutorial that will show me the basics which will include:

1. Downloading the video file from the web
2. Storing it in a data store for my application (what structure / location)
3. Playing this video from my data store
4. What video format I require