How long is World History?

What do you think of when you hear the words “World History”?

John Green believes it is 15,000 years long. He has produced a series of YouTube videos giving what he thinks are the main facts in the story.

Not sure if he is aware of the preceding 4,600 million.

(Admittedly he does call it a “crash course” but this crash seems to have telescoped the story down to almost nothing.