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="Nastroika3.png|5" />
  </query-continue>
  <query>
    <pages>
      <page pageid="5" ns="0" title="Панель управления (биллинг)" />
      <page pageid="14" ns="0" title="DNS записи" />
      <page pageid="17" ns="0" title="DNS хосты" />
      <page pageid="22" ns="0" title="Нейм сервера (NS)" />
      <page pageid="75" ns="0" title="Регистрация/продление доменов" />
      <page pageid="76" ns="0" title="Регистрация/продление домена" />
    </pages>
  </query>
</api>