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="Batch_sparging_efficiency_formulas.gif|1458" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:BSPGS 1st and 2nd run off.gif" />
      <f ns="6" title="File:BSPGS 1st recharge.gif" />
      <f ns="6" title="File:BSPGS 1st run off.gif" />
      <f ns="6" title="File:BSPGS boil off.gif" />
      <f ns="6" title="File:BSPGS equipment.gif" />
      <f ns="6" title="File:BSPGS initial mash.gif" />
      <f ns="6" title="File:BSPGS units.gif" />
      <f ns="6" title="File:Batch 61 iodine test.jpg" />
      <f ns="6" title="File:Batch 61 iodine test.jpg" />
      <f ns="6" title="File:Batch 77 bruchbilder.jpg" />
    </allfileusages>
  </query>
</api>