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="Mind_sun_aplha_color.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="155" ns="6" title="File:B After TheBall04 50.jpg" />
      <page pageid="154" ns="6" title="File:B Before TheBall03 50.jpg" />
      <page pageid="156" ns="6" title="File:B ColorChange TheBall06 50.jpg" />
      <page pageid="159" ns="6" title="File:Before TheBall.jpg" />
      <page pageid="37" ns="6" title="File:Before TheBall01 85 - Copy.jpg" />
      <page pageid="121" ns="6" title="File:Before TheBall02 50.jpg.jpg" />
      <page pageid="39" ns="6" title="File:Before TheBall03 50.jpg" />
      <page pageid="62" ns="6" title="File:Blue Activated TheBall05 50.jpg" />
      <page pageid="87" ns="6" title="File:Lava TheBall08 50.jpg" />
      <page pageid="70" ns="6" title="File:Mind sun alpha1.jpg" />
    </pages>
  </query>
</api>