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="IMG_2402.jpg|340" />
  </query-continue>
  <query>
    <pages>
      <page pageid="217" ns="10" title="Шаблон:Избранная фотка" />
      <page pageid="267" ns="0" title="Заглавная страница" />
      <page pageid="301" ns="0" title="Статьи Анатолия в Википедии" />
      <page pageid="306" ns="0" title="Фотогалерея Анатолия" />
      <page pageid="340" ns="0" title="Давина" />
      <page pageid="391" ns="0" title="Фрося" />
    </pages>
  </query>
</api>