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="Begraafplaats_Moscowa_(Arnhem).jpg|950" />
  </query-continue>
  <query>
    <pages>
      <page pageid="47" ns="0" title="Barend Barendse (1907-1981)" />
      <page pageid="61" ns="0" title="Barend Biesheuvel" />
      <page pageid="515" ns="0" title="Ien Dales" />
      <page pageid="1170" ns="0" title="Bart Peizel" />
      <page pageid="1273" ns="0" title="Bart van der Leck" />
      <page pageid="1418" ns="0" title="Bart Kreeft" />
      <page pageid="2037" ns="0" title="Bab Wijsman" />
    </pages>
  </query>
</api>