An active contemporary discourse on YouTube revolves around the idea that the Earth is flat instead of round, and how Flat Earth cosmology is related to contemporary political, religious and cultural issues. Thousands of such videos have been produced, gathering multiple millions of views. Flat Earth discourse sometimes crosses into other public discourse, but YouTube remains singularly important in promoting Flat Earth belief and encouraging development of its supporting arguments. The videos at the source of this stir are highly ambiguous. I argue that this phenomenon represents fusion of multiple influences unique to YouTube, including conspiracy theory, climate change denial, science documentaries, clickbait, viral videos, trolling, Russian propaganda, and young-Earth religious fundamentalism. The phenomenon cannot be properly understood without recognizing the distinct contribution of all of these elements.