title: Boosting matched documents in Elasticsearch which have a certain tag
body: <p>I have an index of documents that look this:</p>
  
  <pre><code>{
      url: "/foo/bar",
      html_blocks: [
         "&lt;h1&gt;hi&lt;/h1&gt;"
      ],
      tags: [
          "video",
          "text"
      ],
      title: "My title"
  }
  </code></pre>
  
  <p>I'd like to query these documents on the <em>title</em> and <em>html_blocks</em> fields, and for any matches add a boost if they have a <em>video</em> tag.</p>
  
  <p>So far, my query looks like this:</p>
  
  <pre><code>{
      "query": {
          "query_string": {
              "query": "foo",
              "fields": [
                  "title",
                  "html_blocks"
              ]
          }
      }
  }
  </code></pre>
  
  <p>How do I modify it so that it continues to <strong>only return results if a match is found in the existing query</strong>, but a boost is added to any of the results which have a <em>video</em> tag? Thanks!</p>