Feed burner changed their blog service return results that it returns blocks of javascript similar to:
document.write(\"\\x3cdiv class\\x3d\\x22feed
That is a PHP Twig encoding:
http://www.twig-project.org/
Since you are using C# you will most likely have to create a dictionary to translate the symbols and then use a series of .Replace()
string methods to convert those back to HTML characters.
Alternatively you can save that data to a file, run a Perl script to decode the text and then read from the file in C#, but that might be more costly.