flat relative to what? the median of the sun? from what angle?
If you watch the video, which I'm guessing you didn't, because it answered your question.
Basically the question boils down to, when a lot of things orbit the same center of mass, why do their orbits all roughly align to the same plane?
I understand that the conservation of angular momentum amplifies any initial tiny spin... however... I was commenting on the fact that the sun also demonstrates precession and itself traveling thru the milky way... so the point of anything being flat is relative to what? when?