...and get this error message
Fatal error: Cannot override final method HTMLPurifier_VarParser::parse()
you can fix this by adding
Configure::write('HtmlPurifier.standalone', true);to your bootstrap.php before you load this plugin.
This line will use a compacted one file version of Html Purifier. This is an official and know issue and workaround, see http://htmlpurifier.org/phorum/read.php?3,4099,6680.