I think the whole debatable issue rests upon the way those brits made fun of the old man. But maybe it's a differnce in culture. The respect for elders is not as strong for Caucasians as for us Asians. And ang mohs can get really crazy sometimes which to us is just disrespectful.
Whenever I travel to the West, I never fail to meet Caucasians who shout for no reason or talk loudly in the middle of the street at night. I hardly see such behavior happening here. They love to party, they love freedom for speech, maybe that's why. They say whatever they want. They get terribly drunk and they think that's fun.
In the Singapore context, what those chaps did on Youtube is a big No-no. I think it looks darn disrespectful and silly in our culture.