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="Batty" />
  </query-continue>
  <query>
    <pages>
      <page pageid="4125" ns="0" title="Back To The Future" />
      <page pageid="4128" ns="0" title="Back To The Future Part II" />
      <page pageid="4129" ns="0" title="Back To The Future Part III" />
      <page pageid="11636" ns="0" title="Back to Skool" />
      <page pageid="4600" ns="0" title="Bacteria" />
      <page pageid="4091" ns="0" title="Bajtek" />
      <page pageid="3163" ns="0" title="Barbarian" />
      <page pageid="6067" ns="0" title="Batman the Caped Crusader" />
      <page pageid="5825" ns="0" title="Battle City (1993)" />
      <page pageid="6432" ns="0" title="Battlezone" />
    </pages>
  </query>
</api>