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>
    <allredirects garcontinue="CELayoutEditor_Manual|1529" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1779" ns="0" title="Build from Source for Win32" />
      <page pageid="1781" ns="0" title="Build Configuration For Irrlicht" />
      <page pageid="1806" ns="0" title="CEGUI InPractice 1" />
      <page pageid="1807" ns="0" title="CEGUI InPractice 2" />
      <page pageid="1812" ns="0" title="CEGUI InPractice 3" />
      <page pageid="1813" ns="0" title="CEGUI InPractice 4" />
      <page pageid="1814" ns="0" title="CEGUI InPractice 5" />
      <page pageid="1833" ns="0" title="CEGUI InPractice 6" />
      <page pageid="1837" ns="0" title="CEGUI In Practice7" />
      <page pageid="1844" ns="0" title="Auto Repeat Key" />
    </pages>
  </query>
</api>