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>
    <allimages gaicontinue="Btn_Tools_Draw.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="5" ns="6" title="File:Btn Bezier.png">
        <duplicatefiles>
          <df name="Btn_Tools_Bezier.png" user="Greg" timestamp="2013-03-20T13:22:15Z" />
        </duplicatefiles>
      </page>
      <page pageid="21" ns="6" title="File:Btn Layer Delete.png" />
      <page pageid="22" ns="6" title="File:Btn Layer Guide.png" />
      <page pageid="25" ns="6" title="File:Btn Layer Mirror.png" />
      <page pageid="23" ns="6" title="File:Btn Layer New.png" />
      <page pageid="24" ns="6" title="File:Btn Layer SelectAll.png" />
      <page pageid="27" ns="6" title="File:Btn Slices Slat.png" />
      <page pageid="28" ns="6" title="File:Btn Slices Slice.png" />
      <page pageid="26" ns="6" title="File:Btn Slices SliceGrp.png" />
      <page pageid="7" ns="6" title="File:Btn Tools Bezier.png">
        <duplicatefiles>
          <df name="Btn_Bezier.png" user="Greg" timestamp="2013-03-20T13:16:27Z" />
        </duplicatefiles>
      </page>
    </pages>
  </query>
</api>