A new set of functionality enhancements being released today to Web developers could enable them to build customized video libraries around their exclusive sites, with YouTube doing less to steal their users away.

Up to now, when you've seen a YouTube video appear embedded in a Web site (such as our own), it has had its own somewhat generic look and feel. And in recent months, you've seen that it has embedded search features which let viewers who've seen the first embedded video, go on to search for material that may be related or completely unrelated. In a way, that converts Web site users into YouTube users, albeit indirectly.

Beginning today, you might see that start to change with YouTube's release of a new and refreshed set of developer APIs. Among the functionality exposed in the latest set is what YouTube's programmers are calling a "chrome-less player" -- essentially, a very generic version of the Flash-based YouTube player control, designed to enable Web sites to develop their own unique look-and-feel locally, without paying anyone a license fee.

And as YouTube's team announced this morning, sites will be able to create their own private video libraries, utilizing their own users' accounts and categorized through custom tags embedded in the stream. This way, a site can build up its own collection of videos that are specially tagged for custom sites, though stored on and streamed through YouTube.

"You can now have users sign into YouTube from your own Web site," reports YouTube Engineering Manager John Harding in a video released this morning. "That's going to let them upload videos to their account, modify playlists, add favorites -- all the stuff they can do on YouTube, they can now do on your site with their account."

That uploading feature is important, because now sites can build their custom libraries through their users' own submissions, by way of direct downloads.

Client authorization will be available using either of two methods, according to a developer team blog post this morning: setting up a proxy for a Web service or Web application and authorizing the user through that, or directly authorizing the user through an installed application such as a presentation system.

The chrome-less player could be used within such a system to present a custom experience for the user without the generic YouTube appearance.

"In the past, all you could really do when you wanted to embed the YouTube player was just stick it there on your page," said Harding, "and you could either have it play or not. So now we actually have a whole set of JavaScript and Flash APIs that you can use to control the player either from JavaScript on the page or your own Flash."

Play, pause, seek to a specific time, volume, mute, and current play time will be among the console functions which developers can attribute to specific customized gadgets.

Although not much has been said on this topic today, those submissions will probably also be accessible directly by default from YouTube. However, a check of the revised Terms of Service for the revised YouTube API this morning reveals that developers won't be bound by much except for one standing rule: If YouTube has to remove a video from its collection, API users will be expected to do their utmost to ensure that the removed video doesn't also appear to be available through their sites.

"You can employ session based caching of YouTube API results but must use commercially reasonable efforts to update cached results upon any changes in video metadata," reads the new Terms. "For example, if a video is removed from the YouTube service or made 'private' by the video uploader, cached results and thumbnails should be removed from Your cache."

That revelation also directly refers to the uploader's ability to make videos private, which could presumably be extended to sites that use the API for their own libraries. Nothing in the Terms specifies that videos uploaded to YouTube must be available to all YouTube users.

"We do all of the hard work of transcoding and hosting and streaming and thumbnailing your videos, and we provide open access to our sizable global audience, enabling you to generate traffic for your site, visibility for your brand, or support for your cause," reads a statement to developers from the company this morning. "Meanwhile, we provide full access to our substantial video library, enabling you to attract users and enhance the experience on your site. It's all free, and it's available to everyone, starting now."

Apparently, an early form of the new API was already used by TiVo, which announced this morning it has adapted YouTube's services for use in its subscribers' DVRs.