title: How to exclude some domains from a URL pattern?
body: <p>I'm trying to fetch online vedio and its descriptions. youtube and several others that provides api accesses work fine. For the rest of website, I will use oEmbed. 
  So, for youtube, if pattern match this:</p>
  
  <pre><code>/^http:\/\/(www\.)?youtube.com\/watch/
  </code></pre>
  
  <p>then, it will use "yt custom service" to fetch content.</p>
  
  <p>For the rest of the site, will use oEmbed service:</p>
  
  <pre><code>preg_match_all('`.*?((http|https)://[\w#$&amp;+,\/:;=?@.-]+)[^\w#$&amp;+,\/:;=?@.-]*?`i', $content, $matches);
  </code></pre>
  
  <p>So, how can I exclude youtube and several others from this match_all pattern?</p>