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="Basemesh_arshlevon_toes.obj|55" />
  </query-continue>
  <query>
    <allfileusages>
      <f fromid="1369" ns="6" title="File:BRDF Brice-Vandemoortele.jpg" />
      <f fromid="55" ns="6" title="File:Basemesh 01.gif" />
      <f fromid="55" ns="6" title="File:Basemesh 01.obj.zip" />
      <f fromid="55" ns="6" title="File:Basemesh Body Anzhou.zip" />
      <f fromid="55" ns="6" title="File:Basemesh Bust Anzhou.zip" />
      <f fromid="55" ns="6" title="File:Basemesh anzhou body.gif" />
      <f fromid="55" ns="6" title="File:Basemesh anzhou bust.gif" />
      <f fromid="55" ns="6" title="File:Basemesh arshlevon shoes.gif" />
      <f fromid="55" ns="6" title="File:Basemesh arshlevon shoes.obj" />
      <f fromid="55" ns="6" title="File:Basemesh arshlevon toes.gif" />
    </allfileusages>
  </query>
</api>