This is literally the best pro-union ad I've seen, and he's being facetious.

If you weren't aware, or were only just dimly aware, something really important is happening this week in world history: the Scottish people may elect to leave the United Kingdom, which would mean the end of Britain as we know it. Yes, Britain, the empire that America once rebelled against, the empire that once controlled over 20% of the world's surface and population, and that place James Bond is from. However mighty and proud the British Empire became, it all started with England forcing the nearby realms of Scotland, Wales and Ireland (now just Northern Ireland) into the United Kingdom. If Scotland gains independence, it will be the first time since the Enlightenment that London was no longer the capital of a united island, never mind an empire. In short, this is a big f-ing deal, as Englishman-turned-American-fake-newscaster John Oliver explains.

Sources: Last Week Tonight with John Oliver