You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Comparator-ICS.png|161" />
  </query-continue>
  <query>
    <pages>
      <page pageid="26" ns="0" title="Movies" />
      <page pageid="75" ns="0" title="Tuomas Varnsson" />
      <page pageid="77" ns="0" title="Lidia Vaitarosa" />
      <page pageid="103" ns="0" title="T-shirts and other merchandising" />
      <page pageid="136" ns="0" title="Number of volumes in the Library of Babel" />
      <page pageid="154" ns="0" title="Italian Fascism and German Nazism" />
      <page pageid="161" ns="0" title="Inchrosil" />
      <page pageid="165" ns="0" title="Heim theory" />
    </pages>
  </query>
</api>