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="Http://farm6.staticflickr.com/5096/5435802811_c442abdca6.jpg" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="Файл:D2501ac4b3.jpg" />
      <f ns="6" title="Файл:Http://farm1.staticflickr.com/124/356268993 34c4fce2b3.jpg" />
      <f ns="6" title="Файл:Http://farm1.staticflickr.com/16/20008142 27242bc1e4.jpg" />
      <f ns="6" title="Файл:Http://farm1.staticflickr.com/171/412618381 eb73f9dc5b.jpg" />
      <f ns="6" title="Файл:Http://farm2.staticflickr.com/1069/5137462094 6a73a9ec60.jpg" />
      <f ns="6" title="Файл:Http://farm4.staticflickr.com/3110/2715583000 d87171f627.jpg" />
      <f ns="6" title="Файл:Http://farm4.staticflickr.com/3546/3829936845 bdf2760185.jpg" />
      <f ns="6" title="Файл:Http://farm4.staticflickr.com/3733/9207703550 3b65bf2f06.jpg" />
      <f ns="6" title="Файл:Http://farm5.staticflickr.com/4091/4987783720 5fca08ecd4.jpg" />
      <f ns="6" title="Файл:Http://farm6.staticflickr.com/5022/5624656454 7969418b37.jpg" />
    </allfileusages>
  </query>
</api>