I'm doing this to enable Airplay on HTML5 video for my iPad 1st generation with iOS 4.3.1.
// Prototype JS framework
Try reformatting it as a .mp4 movie, and make sure that it is H.264 video with AAC audio. It has to be H.264, or the iPad can't steam it. (Got this from http://macosrumors.com/2011/01/12/first-look-mobile-safari-airplay/)