He's not funny.
And this idea that Trump's campaign will have turned out to be a joke the whole time is the height of liberal fantasy. They can't accept that people actually agree with Trump or like him.
Trump derangement syndrome is a thing. Fortunately, John Oliver is probably less influential than Larry Wilmore and anyone who finds this video funny isn't going to vote for Trump anyway.
BTW, I love Oliver. I think he is (usually) funny and this bit wasn't bad at all, but this odd belief that people like Oliver, Jon Stewart, or Trevor Noah have any influence or pull at all is very, very annoying.