On the iPhone and iPod, if a YouTube video is embedded in a web page, the user can touch the video and the video will start playing—the iOS media player slides in and the vi
From the Safari documentation:
"Important: The webkitEnterFullscreen() method can be invoked only in response to a user action, such as clicking a button. You cannot invoke webkitEnterFullscreen() in response to an onload() event, for example."
That might explain why your webkitEnterFullscreen is always false.
http://developer.apple.com/library/safari/documentation/AudioVideo/Conceptual/Using_HTML5_Audio_Video/ControllingMediaWithJavaScript/ControllingMediaWithJavaScript.html#//apple_ref/doc/uid/TP40009523-CH3-SW13
Jan's solution handling the 'ended' event is the best in your case.