An 8-minute plain-language explainer of OpenAI's September 2026 Navier-Stokes claim: what the equations describe, why stretching swirls could make speed blow up (with numbers you can check), a real 2D fluid simulation computed for this video, the Millennium Prize's two doors, what OpenAI claimed (a blow-up with a smooth outside push), the catch (the push does the steering; the no-push question is still open), and where verification stands as of Oct 20, 2026 (claimed, Lean mismatch reported, not independently confirmed).