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="Betty_wellinton_nursing.jpg|972" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:BR-3-006 Prelim group May 1967.jpg" />
      <f ns="6" title="File:BR-3-007 After-Finals Ball.jpg" />
      <f ns="6" title="File:Bed making.jpg" />
      <f ns="6" title="File:Benson Grace 002.mp3" />
      <f ns="6" title="File:Benson Grace 003.mp3" />
      <f ns="6" title="File:Benson Grace 004.mp3" />
      <f ns="6" title="File:Benson Grace 005.mp3" />
      <f ns="6" title="File:Beryl Hughes Abstract.docx" />
      <f ns="6" title="File:Beryl Hughes Abstract.docx" />
      <f ns="6" title="File:Betty nurse 1940 (2).jpg" />
    </allfileusages>
  </query>
</api>