Swing planes - downswing (green) is outside the backswing (red). This is what is referred to as "over the top". This move is more or less what puts the slice spin on the ball. You can see that your hands and the club are striking across the ball from outside to in.
It looks like your shoulders are open at address and your feet are along the target line. Since the arms and hands are directed by the shoulder line this leaves little choice as to where the arms and hands go. In your swing plane shot here, we can see that your swing plane (green) is similar to the open shoulders (green) line in the diagram.
You could try closing your shoulders a bit at address and see if swinging to the inside on the downswing is a bit easier. The three ball drill can't be done if your shoulders, hands, and arms are going out to in on the downswing.
Good question on the driver shaft. If possible I suggest to visit a golf store with an electronic driving bay, or a fitter who can measure your swing speed. Hard to tell if that's video glitch/blur or the actual shaft.
