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 afcontinue="SEO_Australia_5035.jpg" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:Certification 1522.jpg" />
      <f ns="6" title="File:Certification 3776.jpg" />
      <f ns="6" title="File:Drop Shipping Companies, Drop Ship Companies 2353.jpg" />
      <f ns="6" title="File:Hvac install 4561.jpg" />
      <f ns="6" title="File:Insurance 1891.jpg" />
      <f ns="6" title="File:Insurance 2587.jpg" />
      <f ns="6" title="File:Insurance 2604.jpg" />
      <f ns="6" title="File:Insurance 3153.jpg" />
      <f ns="6" title="File:Insurance 3710.jpg" />
      <f ns="6" title="File:PearStory EXMARaLDA.xml" />
    </allfileusages>
  </query>
</api>