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="Benutzerkonto4.jpg|6932" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1430" ns="0" title="BIOS" />
      <page pageid="3872" ns="0" title="Standard Backupprogramm ändern" />
      <page pageid="4296" ns="0" title="In der Kommandozeile schnell eine Batch-Datei erstellen" />
      <page pageid="5958" ns="0" title="Befehlssatz" />
      <page pageid="6586" ns="0" title="Small Business Server 2008" />
      <page pageid="6932" ns="0" title="Windows 7 Benutzerkontensteuerung" />
    </pages>
  </query>
</api>