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>
    <alltransclusions gatcontinue="Cc-by-sa-3.0|377" />
  </query-continue>
  <query>
    <pages>
      <page pageid="33" ns="6" title="File:Markov.png" />
      <page pageid="34" ns="6" title="File:Markov2.png" />
      <page pageid="35" ns="6" title="File:Markov Chain.png" />
      <page pageid="36" ns="6" title="File:Pressfit1.png" />
      <page pageid="37" ns="6" title="File:Vigrasamlagning.png" />
      <page pageid="372" ns="6" title="File:P4140627.JPG" />
      <page pageid="373" ns="6" title="File:SS5 DSCN9438.JPG" />
      <page pageid="374" ns="6" title="File:SS5 DSCN9439.JPG" />
      <page pageid="375" ns="6" title="File:SS5 DSCN9440.JPG" />
      <page pageid="376" ns="6" title="File:SS5 DSCN9441.JPG" />
    </pages>
  </query>
</api>