I watched that. He is furious at them, isn't he? When they call him fascist, he points that he's a Marxist and how is grandfather mutilated himself so he wouldn't have to fight in Hitler's war.
What's obvious from this footage and the rave footage and pretty much every footage is they they have no counter except Fascist, Nazi etc.
What is really interesting is the footage from Ali (the Muslim guy who is another regular at Speakers Corner). I haven't watched all of it but there's just noise, but no calling a Muslim man a Nazi or a fascist. He asks them " If you can't drink till you're 18, how can children change/know their genders?"
I'll see if I can get a link.