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 afcontinue="Ephemeral_time.jpg|224" />
  </query-continue>
  <query>
    <allfileusages>
      <f fromid="202" ns="6" title="File:Bits and pieces - 29-12-13.jpg" />
      <f fromid="43" ns="6" title="File:Chemical interfaces - 12-4-12.jpg" />
      <f fromid="190" ns="6" title="File:Clarity in existence - 26-7-13.jpg" />
      <f fromid="190" ns="6" title="File:Clarity in existence 2 - 26-7-13.jpg" />
      <f fromid="142" ns="6" title="File:Coincidence - 7-11-12.jpg" />
      <f fromid="106" ns="6" title="File:Difference - 30-1-13.jpg" />
      <f fromid="84" ns="6" title="File:Dysfunctionality in evolution - 20-7-12.jpg" />
      <f fromid="84" ns="6" title="File:Dysfunctionality in evolution 2 - 20-7-12.jpg" />
      <f fromid="84" ns="6" title="File:Dysfunctionality in evolution 3 - 20-7-12.jpg" />
      <f fromid="165" ns="6" title="File:Emotion and will - 22-5-13.jpg" />
    </allfileusages>
  </query>
</api>