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="Banjo_Billy_Jingle_Jangle_Comics.png" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:BabyBrainsCD.jpg" />
      <f ns="6" title="File:Backseat Boys Deadpool.jpg" />
      <f ns="6" title="File:Bad Moves Craig of the Creek.png" />
      <f ns="6" title="File:Bagpiper Lego picA0681ECE38DF543BD5E64A548A409CF2.jpg" />
      <f ns="6" title="File:Bahama Knights Portlandia.png" />
      <f ns="6" title="File:Bailey Sue T-Man.png" />
      <f ns="6" title="File:Baker Nick Boy Loves Girl.png" />
      <f ns="6" title="File:Ballocaust.png" />
      <f ns="6" title="File:Band-square3.JPG" />
      <f ns="6" title="File:Bane Rena Love Diary.png" />
    </allfileusages>
  </query>
</api>