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>
    <allredirects arcontinue="CAAD" />
  </query-continue>
  <query>
    <allredirects>
      <r ns="0" title="BASIC" />
      <r ns="0" title="Batería de iones de litio" />
      <r ns="0" title="Bawareth Perfect MSX1" />
      <r ns="0" title="Bits por segundo" />
      <r ns="0" title="Boxeo" />
      <r ns="0" title="Bull" />
      <r ns="0" title="Bulletin Board System" />
      <r ns="0" title="Bus ISA" />
      <r ns="0" title="Byte" />
      <r ns="0" title="C.ITOH ProWriter Junior" />
    </allredirects>
  </query>
</api>