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="Bot_detection.jpg" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:Banner en backend banner.jpg" />
      <f ns="6" title="File:Banner en backend banner new.jpg" />
      <f ns="6" title="File:Banner en backend bannerstatistic.jpg" />
      <f ns="6" title="File:Banner en backend category new.jpg" />
      <f ns="6" title="File:Banner en frontend all banner.jpg" />
      <f ns="6" title="File:Banner en frontend one banner.jpg" />
      <f ns="6" title="File:Be user online en member.jpg" />
      <f ns="6" title="File:Be user online en user.jpg" />
      <f ns="6" title="File:Beginner.png" />
      <f ns="6" title="File:Bom checker er.jpg" />
    </allfileusages>
  </query>
</api>