<?php
 
$input = "http://w...content-available-to-author-only...e.com/watch?v=itvJybdcYbI text [url=http://s...content-available-to-author-only...e.com/watch?v=itvJybdcYbI]What's up?[/url] text youtube.com/watch?v=itvJybdcYbI text www.youtube.com/watch?v=itvJybdcYbI";
 
echo can_haz_linkz($input)? 'Y': 'N';
 
$input = "text [url=http://s...content-available-to-author-only...e.com/watch?v=itvJybdcYbI]What's up?[/url] text";
 
echo can_haz_linkz($input)? 'Y': 'N';
 
function can_haz_linkz($input)
{
    return preg_match(
        "#([\w-]+:\/\/?|(www|([\w]+))[.])[^\s()<>\[\]]+(?:\([\w\d]+\)|([^[:punct:]\s]|\/))#is", 
        (preg_replace("#\[url=(.*?)/url\]#is", '', $input))
    );
}

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