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="CV_Boot_01.jpg|411" />
  </query-continue>
  <query>
    <allfileusages>
      <f fromid="285" ns="6" title="File:Balance shafts.gif" />
      <f fromid="554" ns="6" title="File:Bezels and rings.jpg" />
      <f fromid="332" ns="6" title="File:Bleeding Sensonic.gif" />
      <f fromid="516" ns="6" title="File:Blower Diagnostic 01.gif" />
      <f fromid="516" ns="6" title="File:Blower Diagnostic 02.gif" />
      <f fromid="516" ns="6" title="File:Blower Diagnostic 03.gif" />
      <f fromid="516" ns="6" title="File:Blower Diagnostic 04.gif" />
      <f fromid="516" ns="6" title="File:Blower Diagnostic 05.gif" />
      <f fromid="516" ns="6" title="File:Blower Diagnostic 06.gif" />
      <f fromid="282" ns="6" title="File:Bottom end.jpg" />
    </allfileusages>
  </query>
</api>