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="Bardiche.jpg" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3786" ns="6" title="File:BM59 bayo.jpg" />
      <page pageid="143" ns="6" title="File:BMS Milcam HB.jpg" />
      <page pageid="2674" ns="6" title="File:BRR crossbow.jpg" />
      <page pageid="149" ns="6" title="File:BSA Lewis gun.JPG" />
      <page pageid="5757" ns="6" title="File:BSA Welrod Mk I.jpg" />
      <page pageid="3702" ns="6" title="File:BUR rocket.jpg" />
      <page pageid="2766" ns="6" title="File:Ballistic knife.jpg" />
      <page pageid="2712" ns="6" title="File:Barbed Lucille.jpg" />
      <page pageid="2796" ns="6" title="File:Barbed nine-tails.jpg" />
      <page pageid="5400" ns="6" title="File:Barbed spear.jpg" />
    </pages>
  </query>
</api>