selection.js

$('#id_video_id').live('paste', function() {
  var onFail = function(found) {
    alert('Unsupported video service or invalid URL');
    console.log(found);
    $(element).val('');
    return false;
  }
  var element = this;
  var parser = document.createElement('a');
  setTimeout(function () {
      parser.href = $(element).val();
      var videoId = new String();
      if (parser.hostname === "youtu.be") {
        videoId = parser.pathname.replace('/', '');
        $(element).val(videoId);
      }else if(parser.hostname === "youtube.com" || parser.hostname === "www.youtube.com" ) {
        var matches = parser.search.match(/v\=([A-Za-z0-9\-]+)/);
        if (matches[1]) {
          videoId = matches[1];
          $(element).val(videoId);
        } else {
          onFail(parser.href);
        }
      } else {
        onFail(parser.href);
      }
    }, 300);
});