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="NonMotorized_HBW1.jpg|1" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:BWI Accessibility.jpg" />
      <f ns="6" title="File:Case1 TOD.jpg" />
      <f ns="6" title="File:Case2 Amazon.jpg" />
      <f ns="6" title="File:Case3 CSX.jpg" />
      <f ns="6" title="File:Case4 ArundelMills.jpg" />
      <f ns="6" title="File:Case5 MultiModal.jpg" />
      <f ns="6" title="File:FAF Processing.jpg" />
      <f ns="6" title="File:Job Accessibility.jpg" />
      <f ns="6" title="File:MC Validation.jpg" />
      <f ns="6" title="File:MSTM Overview.jpg" />
    </allfileusages>
  </query>
</api>