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="11543089_10153450246182287_1815517383_o.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1601" ns="6" title="File:--Category-The Fall of Virtus Prime--.jpeg" />
      <page pageid="1602" ns="6" title="File:--Category-The Fall of Virtus Prime2--.jpeg" />
      <page pageid="2848" ns="6" title="File:--Category-The Siege of Iulia Augusta--.jpeg">
        <duplicatefiles>
          <df name="Image8_-629201-.jpeg" user="Allart" timestamp="2015-12-06T22:10:55Z" />
        </duplicatefiles>
      </page>
      <page pageid="3792" ns="6" title="File:--Category-Þungur Metallikos~Probing Action aboard Abandoned Void Station--.jpeg">
        <duplicatefiles>
          <df name="Setup.jpeg" user="Swordchuck" timestamp="2016-06-16T05:01:30Z" />
        </duplicatefiles>
      </page>
      <page pageid="6632" ns="6" title="File:09BDCC93-B950-4FB6-A241-94EFCE6BAE70.jpeg" />
      <page pageid="4391" ns="6" title="File:100px-Legio III Tactical Mk III.png" />
      <page pageid="2462" ns="6" title="File:100px-legio XVI.png" />
      <page pageid="2429" ns="6" title="File:103rd Battalion livery.jpg" />
      <page pageid="3134" ns="6" title="File:110px-Legio X.png" />
      <page pageid="2281" ns="6" title="File:11144441 10207515330705518 442253376461232583 o.jpg" />
    </pages>
  </query>
</api>