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="Bonitas.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="198" ns="6" title="Bestand:B79E5776-5A7A-44AA-8D65-389E70127FBF.jpg" />
      <page pageid="82" ns="6" title="Bestand:Bambi aan het werk.jpg" />
      <page pageid="79" ns="6" title="Bestand:Bambi in Rotterdam.jpg" />
      <page pageid="21" ns="6" title="Bestand:Bolnes Fabriekshal 1950.jpg" />
      <page pageid="65" ns="6" title="Bestand:Bolnes Harmonie III.jpg" />
      <page pageid="196" ns="6" title="Bestand:Bolnes Mevo 2.jpg" />
      <page pageid="195" ns="6" title="Bestand:Bolnes Mevo 2 type plaatje.jpg" />
      <page pageid="22" ns="6" title="Bestand:Bolnes gloeikopmotoren.jpg" />
      <page pageid="86" ns="6" title="Bestand:Bolnes wimpel.jpg" />
      <page pageid="101" ns="6" title="Bestand:Bolnes wimpel foto.jpg" />
    </pages>
  </query>
</api>