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 gafcontinue="Benajmin.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3328" ns="6" title="File:Backpack diagram.jpg" />
      <page pageid="3320" ns="6" title="File:Backpack straps.jpg" />
      <page pageid="2222" ns="6" title="File:Bathroom Door 3D.jpg" />
      <page pageid="2223" ns="6" title="File:Bathroom Eye Count 3D.jpg" />
      <page pageid="2224" ns="6" title="File:Bathroom From Interlock 3D.jpg" />
      <page pageid="2225" ns="6" title="File:Bathroom Looking Into Interlock 3D.jpg" />
      <page pageid="2226" ns="6" title="File:Bathroom Wall 3D.jpg" />
      <page pageid="3487" ns="6" title="File:Bees.png" />
      <page pageid="3649" ns="6" title="File:Ben nun.jpg" />
      <page pageid="2339" ns="6" title="File:Ben paul.JPG" />
    </pages>
  </query>
</api>