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="DSC07950.jpeg|756" />
  </query-continue>
  <query>
    <pages>
      <page pageid="600" ns="0" title="Interventions d&#039;APAïstes à la médiathèque de Muret" />
      <page pageid="623" ns="106" title="MP:Journal de Claire Diterzi" />
      <page pageid="729" ns="106" title="MP:Maryse Bernède" />
      <page pageid="736" ns="106" title="MP:Myriam Marchioro" />
      <page pageid="756" ns="106" title="MP:Janine Bonnotte" />
      <page pageid="866" ns="106" title="MP:Expérience d&#039;écriture collective d&#039;un roman" />
      <page pageid="895" ns="106" title="MP:Psychologie et alchimie" />
      <page pageid="908" ns="108" title="Fonds:BNF" />
    </pages>
  </query>
</api>