Sam's Tetrahedron

Sam Shah posed the problem: put a point D on an ellipsoid $x^2/A^2+y^2/B^2+z^2/C^2=1$. What's the minimum volume of the tetrahedron formed by tangent plane at D and the 3 coordinate planes? Felt so intuitive, I wanted to model it. Do you believe Sam's formula? What is this formula?