waider | stylish (and somewhat pointless) heckling

Youtube ahead: hecklers sing in harmony to interrupt Jack Straw. Really, though, they got a round of applause, laughter, and the hecklee (?) immediately riffed on their performance. So how successful a heckle was it, really?

(I probably got this on Metafilter; I've been accumulating browser tabs on and off all day)