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"?>
    <alltransclusions gatcontinue="BlueBox_Message|5039" />
      <page pageid="1143" ns="0" title="GDI Black Gold" />
      <page pageid="2782" ns="0" title="Compro VideoMate E700" />
      <page pageid="2999" ns="10" title="Template:ArticleNeedsExpanding" />
      <page pageid="3022" ns="0" title="AVerMedia M791 PCIe Combo (OEM)" />
      <page pageid="3032" ns="0" title="Pinnacle PCTV Dual Hybrid Pro PCI Express (3010i)" />
      <page pageid="3164" ns="0" title="Compro VideoMate E650" />
      <page pageid="3176" ns="0" title="AVerMedia M792 PCIe Combo (OEM)" />
      <page pageid="3259" ns="0" title="Compro VideoMate E800F" />
      <page pageid="3304" ns="0" title="Compro VideoMate E600F" />
      <page pageid="3799" ns="0" title="AVerMedia AVerTV Hybrid Speedy PCI-E" />