That is a very clever political ad! You don't "get it" until the end. Watch it, everyone!
Now, pardon me if my ignorance is showing, but is a "riding" a voting district? Is it determined by population?
Also, are you just voting for prime minister or also representatives for parliament? The US splits those elections up, but I shouldn't assume it's the same everywhere.
And, is it "winner takes all" or is there proportional representation?
I apologize for my ignorance, but in my 16 plus years of education I have never once learned anything about the Canadian government. Pretty pathetic, now that I think of it.