title: How do I find all YouTube video ids in a string using a regex?
body: <p>I have a textfield where users can write anything.</p>
  
  <p>For example:</p>
  
  <blockquote>
    <p>Lorem Ipsum is simply dummy text.
    <a href="http://www.youtube.com/watch?v=DUQi_R4SgWo" rel="noreferrer">http://www.youtube.com/watch?v=DUQi_R4SgWo</a>
    of the printing and typesetting
    industry. Lorem Ipsum has been the
    industry's standard dummy text ever
    since the 1500s, when an unknown
    printer took a galley of type and
    scrambled it to make a type specimen
    book. It has survived not only five
    centuries, but also the leap into
    electronic typesetting, remaining
    essentially unchanged.
    <a href="http://www.youtube.com/watch?v=A_6gNZCkajU&amp;feature=relmfu" rel="noreferrer">http://www.youtube.com/watch?v=A_6gNZCkajU&amp;feature=relmfu</a>
    It was popularised in the 1960s with
    the release of Letraset sheets
    containing Lorem Ipsum passages, and
    more recently with desktop publishing
    software like Aldus PageMaker
    including versions of Lorem Ipsum.</p>
  </blockquote>
  
  <p>Now I would like to parse it and find all YouTube video URLs and their ids.</p>
  
  <p>Any idea how that works?</p>