The YouTube Developers API blog has updated and released a new YouTube API, that will help it become more interesting solution for publishers and social networks.
YouTube no longer restricts you to use their player: the chromeless player lets you add personalized controls, menus, but you can't remove the branding. You can add all of your own buttons and aesthetics to make YouTube fit in with your site, and control it with the player APIs.
Flash APIs are also available with identical calls if you want to load our player into your Flash app.
The other important addition is the support for authentication to allow users to upload videos, comment on videos, manipulate playlists, edit metadata, rate videos, and more, all without leaving your site or application or from desktop applications.
Two types of authentication are now available to allow your users to log into their YouTube accounts on your site. AuthSub (proxy auth for web applications) and ClientLogin (for installed applications). If you've used other Google Data APIs, this should be very familiar to you.