WordPress at a glance
function is not described

wp_oembed_add_provider() WP 2.9.0

Adds a URL format and oEmbed provider URL pair.

No Hooks.

Return

Nothing (null).

Usage

wp_oembed_add_provider( $format, $provider, $regex );
$format(string) (required)
The format of URL that this provider can handle. You can use asterisks as wildcards.
$provider(string) (required)
The URL to the oEmbed provider.
$regex(true/false)
Whether the $format parameter is in a RegEx format.
Default: false

Code of wp oembed add provider: wp-includes/embed.php VER 5.0.3

<?php
function wp_oembed_add_provider( $format, $provider, $regex = false ) {
	if ( did_action( 'plugins_loaded' ) ) {
		$oembed = _wp_oembed_get_object();
		$oembed->providers[$format] = array( $provider, $regex );
	} else {
		WP_oEmbed::_add_provider_early( $format, $provider, $regex );
	}
}