What the !#@$? Does That Mean?

In this series of lessons,  we're working with bringing the heels towards the buttocks, initially mainly in sidelying (456-7) and then on the back in 458-9. In 459, on the back, we're sliding one heel along the floor, closer to the buttock and away, lengthening the leg, with the foot touching the other (long) leg the whole time. Moshe talks about "lowering the knee" while lengthening the foot away, starting in #459 starting in 5--he says things like "and, at the same time, lower the knee down so the movement will be very easy" and (in 6a. for example) "Lower the knee to the floor, in the direction of the floor. It is not important to touch the floor."  So it sounds like the lowering of the knee is optional and something extra you do to make it easier to lower the foot. This to me sounds like lowering the knee to the outside. On the other hand, he never actually says that. Particularly as things go on, it seems more that the knee flexes and extends perpendicular to the floor. In (my sense of) English it doesn't seem normal to call that "lowering the knee." But I suppose literally it could be called this. So I'm not sure I've understood the lesson.