Elep

<?php
/*
Plugin Name: Smart YouTube httpv:// URLs
Description: Parse video URLs used by the Smart YouTube plugin
Version: 1.0
Author: Janis Elsts

ModuleCategory: parser
ModuleClassName: blcSmartYouTubeURL
ModuleContext: on-demand
ModuleLazyInit: true

ModulePriority: 100
*/

if ( ! class_exists( 'blcPlaintextUrlBase' ) ) {
	require_once 'plaintext-url-parser-base.php';
}

class blcSmartYouTubeURL extends blcPlaintextUrlBase {

protected function validate_url( $url ) {
		//Ignore invalid URLs.
		$parts = @parse_url( $url );
		if ( empty( $parts ) ) {
			return false;
		}

//We only care about httpv[hp]:// URLs as used by the Smart YouTube plugin.
		if ( stripos( $parts['scheme'], 'httpv' ) !== 0 ) {
			return false;
		}

//The URL should contain a domain name. AFAIK, Smart YouTube doesn't accept relative URLs.
		if ( empty( $parts['host'] ) || ! strpos( $parts['host'], '.' ) ) {
			return false;
		}

//Replace the plugin-specific scheme with plain old http://.
		$url = preg_replace( '#^httpv[^:]*?:#i', 'http:', $url );

return $url;
	}

/**
	 * Change all occurrences of a given URLs to a new URL.
	 *
	 * @param string $content Look for URLs in this string.
	 * @param string $new_url Change them to this URL.
	 * @param string $old_url The URL to look for.
	 * @param string $old_raw_url The raw, not-normalized URL. Optional.
	 *
	 * @return array|WP_Error If successful, the return value will be an associative array with two
	 * keys : 'content' - the modified content, and 'raw_url' - the new raw, non-normalized URL used
	 * for the modified links. In most cases, the returned raw_url will be equal to the new_url.
	 */
	function edit( $content, $new_url, $old_url, $old_raw_url = '' ) {
		//If the user manually prefixes the URL with "httpv://" or other Smart YouTube scheme
		//then use the URL as-is. Otherwise change the scheme to the prefix from the old URL (if available).
		$new_scheme = @parse_url( $new_url, PHP_URL_SCHEME );
		if ( empty( $new_scheme ) || ( stripos( $new_scheme, 'httpv' ) !== 0 ) ) {
			if ( ! empty( $old_raw_url ) ) {
				$scheme = parse_url( $old_raw_url, PHP_URL_SCHEME );
			} else {
				$scheme = 'httpv';
			}

if ( empty( $new_scheme ) ) {
				$new_url = $scheme . '://' . $new_url;
			} else {
				$new_url = preg_replace(
					'#^' . preg_quote( $new_scheme ) . '://#i',
					$scheme . '://',
					$new_url
				);
			}
		}

return parent::edit( $content, $new_url, $old_url, $old_raw_url );
	}

}