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="Hugh_Neilson_Atkinson_and_Libby.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1381" ns="6" title="File:Bruce County.jpg" />
      <page pageid="1677" ns="6" title="File:Customized Logs Rev 1.11.zip" />
      <page pageid="1472" ns="6" title="File:Daintree History (Fred Morley).doc" />
      <page pageid="1427" ns="6" title="File:Daniel Sarles and grandson Ivan.jpg" />
      <page pageid="1487" ns="6" title="File:Doc.gif" />
      <page pageid="1465" ns="6" title="File:Downtown Tiverton Aug 1989 sml.jpg" />
      <page pageid="1429" ns="6" title="File:Ernest and Flossie Sarles.jpg" />
      <page pageid="1459" ns="6" title="File:Genealogy signature.gif" />
      <page pageid="1433" ns="6" title="File:Grampa&#039;s 70th Birthday May 2, 1957.jpg" />
      <page pageid="1626" ns="6" title="File:Hcard-microformat-button.png" />
    </pages>
  </query>
</api>