Process and integrate data from YouTube into your PHP application with PHP's SimpleXML extension
Summary: The YouTube video sharing site allows Web application developers to access public content through its REST-based developer API. The SimpleXML extension in PHP is ideal for processing the XML feeds generated by this API and using them to build customized PHP applications. This article introduces the YouTube Data API, demonstrates how you can use it to browse user-generated video content; access video metadata, comments and responses; and perform keyword searches.
http://www.ibm.com/developerworks/xml/library/x-youtubeapi/