You are correct. His point is that one can use this trick to install programs that Anti-Virus programs cannot detect, because they are part of the browsers, un

You are correct. His point is that one can use this trick to install programs that Anti-Virus programs cannot detect, because they are part of the browsers, unlike perhaps a service. Because while having control of a system is 'winning', one still wish to do damage relatively undetected (if one's intent is to use the machine as a zombie, for instance). And doing it through Firefox is a very undetectable way to do so.