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="Banalitat.jpg|146" />
  </query-continue>
  <query>
    <pages>
      <page pageid="45" ns="2" title="Usuari:Ceriwden/Full vampiro" />
      <page pageid="52" ns="0" title="Ceriwden/Full" />
      <page pageid="119" ns="0" title="Roger Ullastret de Montsegur/Full" />
      <page pageid="120" ns="0" title="Andrea/Full" />
      <page pageid="121" ns="0" title="Sasha/Full" />
      <page pageid="132" ns="0" title="Simon/Full" />
      <page pageid="134" ns="0" title="Carlos Miralles/Full" />
      <page pageid="136" ns="0" title="Lidia González White/Full" />
      <page pageid="139" ns="0" title="Jaume/Full" />
      <page pageid="141" ns="0" title="Loly/Full" />
    </pages>
  </query>
</api>