Of course the police should be involved.
She has a right to hold an opinion but she doesn't have a right to rabidly spew it all over everyone else. Do you really think people should have to put up with that sort of thing? (I'm going to assume your answer is "no", if it is "yes, even if it was my mum or small child she was talking to", we are not going to agree.)
Do you think people should be taking things into their own hands then, e.g., give her a good slapping? They reprimanded her, so I guess violence would be the next step.
I think everyone on that tram showed great restraint, myself. That's a good thing, we don't really want people fighting in the streets over different opinions they have the right to hold, do we? It would make it awfully difficult to get on with things, "Sorry I'm late, there was a mass brawl on the bus again because someone had some offensive shoes and I had to put three of them down to get to the door."
Therefore we need the police to do something, to demonstrate that being restrained does not mean people get away with it.
The audience of 11 million people on youtube did not see her opinion; the audience saw what britains represent. In my opinion, of course.
She, Mr Anonymous, does most certainly not represent me!
If you choose to be as shallow as to tar the entire populace of the British Isles with the same brush, and allow one YouTube video to be the basis for your opinion of Brits, you're no better than her.
That would be like me assuming all USians are ignorant, geographically-challenged hypocrites, who love guns and violence, on the basis of multiple idiotic statements on international TV channels by Sarah Palin—or numerous other right-wingnut politicians you keep electing.