In this new tutorial on the IBM developerWorks website, they show you how - with a little simple HTML and PHP - to integrate functionality from the YouTube API into your site.

The YouTube video sharing site allows Web application developers to access public content through its REST-based developer API. [...] 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.

They help you get started by outlining the format that the YouTube messages use (Atom feeds) and how to run a query against the API and return back the custom data for things like video categories, popularity and the results of keyword searches.