jquery inserted HTML is rendered as a raw text

You can just trick it with a little jQuery parsing

$('div.desc').html( $('<div />').html(that_string).text() );

FIDDLE

$('div.desc').html(decodeURI(that_string));
//OR
$('div.desc').html($.parseHTML(decodeURI(that_string)));

The decodeURI() function will decode the string so it will output <, > etc.