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="Ball,_der_über_eine_Mauer_fliegt.png|2856" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2961" ns="0" title="Drudel ohne Lösung" />
      <page pageid="2984" ns="0" title="BUMMS" />
      <page pageid="3061" ns="0" title="Bilderdrudel ohne Lösung" />
      <page pageid="3062" ns="0" title="Wörterdrudel ohne Lösung" />
      <page pageid="3294" ns="0" title="Bilderrätsel ohne Lösung" />
      <page pageid="3370" ns="0" title="Bahnknotenpunkt" />
      <page pageid="3487" ns="0" title="Bakterien diztanzieren sich von einer die Penecelin abbekommen hat" />
      <page pageid="4411" ns="0" title="Bachstelzen" />
    </pages>
  </query>
</api>