Science

For an object orbiting a normal planet/star/other object, the orbiting object needs a net force inwards, to make the centripetal acceleration required to cause the velocity to change direction to follow the circular orbit instead of traveling in a straight line. That net force is provided by gravity, and the orbital speed is the speed at which the orbing object can travel so that the gravitational force provides exactly the right amount of centripetal acceleration for that speed and that orbital distance.

Very close to a black hole (but still outside the event horizon) space is so curved, that what is considered a straight line is now bent in a circle. The path that the orbiting object would want to take, if it had no net force on it, would be in a circle around the black hole. This happens at a radius of 1.5 times the radius of the black hole. Normally, the faster you move around in a circle, the more force you need to keep you on your circular path, but in this case, you don't need any force to keep you on the path. This is a problem, because a normally orbiting object uses the gravitational force to provide that force to keep it in circular motion, but in this case we still have the gravitational force, but we don't need it for the orbit. if you were in a rocket, you'd need to constantly fire your engines inwards, just to balance out the gravitational force, but then you could orbit at any speed without adjusting your engines.

Its even weirder inside this radius. Inside 1.5 times the radius of the black hole, what is considered a straight line is actually curved tighter than a circle. Now the centripetal acceleration actually points outwards instead of inwards. The faster you move around your orbit, the harder you need to fire the engines to keep yourself from curving inwards.

Of course if you were around a smallish black hole, the tidal forces would likely be pretty insane at that point, but around supermassive black holes, the area around the event horizon can be pretty uniform from what I understand.