Why does Venus rotate backwards

I heard that It is still actually rotating the way it started but got "flipped over" during the period of the "Great Bombardment" (apparently that occurred many years before I was born)

That sounds the most likely of the scenarios he mentions.

We have this residual attachment to the concept of "the music of the spheres," an old theory from the days before good telescopes, which held that there is a harmony and balance in the heavens, which is actually not there. The most radical example of this is Uranus. It's axial tilt is 97.7 degrees, which means that it rotates almost perpendicular to the plane of the eciptic--like a billiard ball rolling across the table. One of its poles always faces the sun, and one always faces away (not the same one at all times). Its rotational period is 17 hours, so it spins fast on its axis. It takes Uranus 84 earth years to make one circuit around the sun. Strange stuff up there in the heavens.

With Pluto it's the atmosphere rotates backward.