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="Bunny.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="318" ns="6" title="File:Bad Apple MYO.jpg" />
      <page pageid="305" ns="6" title="File:Bald Eagle.png" />
      <page pageid="348" ns="6" title="File:Bead eyes.png" />
      <page pageid="232" ns="6" title="File:Beads.png" />
      <page pageid="352" ns="6" title="File:Bejeweled eyes.png" />
      <page pageid="248" ns="6" title="File:Bells.png" />
      <page pageid="67" ns="6" title="File:Birdeer Ryebase.png" />
      <page pageid="268" ns="6" title="File:Body animation.png" />
      <page pageid="269" ns="6" title="File:Body temperature control.png" />
      <page pageid="328" ns="6" title="File:Bub mascot.png" />
    </pages>
  </query>
</api>