The funny thing is, he's very close to speaking some sort of sense sense. The "Antifascist Action" logo is derived from one used by the KPD-leader front group Antifaschistische Aktion in the 1930s, formed after their original paramilitary wing, the Roter Frontkämpferbund, was banned. Where he veers off course, ploughing through the fields of madness with positively Klannish abandon, is that the current AFA is a decentralised network without explicit political affiliations, whose membership are as a rule actively suspicious of formal political organisations, and for that precisely that reason is avoided like the plague by all Marxist-Leninists, who prefer their own centralised front-organisations.
Notably, it's frequently used alongside the anti-fascist arrows, which was employed by the Social Democratic Party's own paramilitary organisation- it was Weimar Germany, even the moderates had a paramilitary wing- the Eiserne Front, which was explicitly anti-Communist. Symbolism has that sort of tendency to break free of its original institutional context.
At any rate, I imagine that when Civver says "communist flag", he means it in a rather broader sense than the rest of us. A Pride flag would quite likely qualify, for example, or an Israeli flag.