Estimated online attendance for the wedding is around 400 million. Provided YouTube could support that many connection (spoiler alert! It can’t), the estimated bandwidth required is about 800 million megabits per second. That’s if it’s streamed at 720p. Even taking that resolution down to 25% will still be an enormous strain on the modern Internet.
Still interested? Geek.com has a wonderful guide on what to watch and where.