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="Mind_sun_aplha_color.jpg|19" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:B After TheBall04 50.jpg" />
      <f ns="6" title="File:B Before TheBall03 50.jpg" />
      <f ns="6" title="File:B ColorChange TheBall06 50.jpg" />
      <f ns="6" title="File:Before TheBall.jpg" />
      <f ns="6" title="File:Before TheBall01 85 - Copy.jpg" />
      <f ns="6" title="File:Before TheBall02 50.jpg.jpg" />
      <f ns="6" title="File:Before TheBall03 50.jpg" />
      <f ns="6" title="File:Blue Activated TheBall05 50.jpg" />
      <f ns="6" title="File:Lava TheBall08 50.jpg" />
      <f ns="6" title="File:Mind sun alpha1.jpg" />
    </allfileusages>
  </query>
</api>