In the video explanation, he says isosceles... doesn't he mean equilateral?
At timestamp 1:23 in the video, Brent says that triangle ABO, because it has three 60 degree angles, is an isosceles triangle. While that's true, it's also true that a triangle with three 60 degree angles is equilateral (which is a special case of "isosceles"). Either would be true to say about triangle ABO, although it would certainly be more effective to note that this triangle is equilateral. Nice catch!