title: How to get url parameters from a url string?
body: <p>Say I have a text "favorite video url" field in my app, I need a way to tell rails that this is a url and then get be able to get parameters from it, </p>
  
  <p>for instance, if the user inputs
  <a href="http://www.youtube.com/watch?v=RV0-DgsDLhs" rel="nofollow">http://www.youtube.com/watch?v=RV0-DgsDLhs</a></p>
  
  <p>I want to be able to get the 'v'param and store it in a variable.</p>
  
  <p>Please help</p>