My current handicap index or average score is:13
My typical ball flight is:draw
The shot I hate or the "miss" I'm trying to reduce/eliminate is:shanks
Do you have a face on view? Yeah the issue isn't the amount the right knee decreases in flex. Head moves down and up (maybe also to the right) and looks like the hips move to your right. I would work on that steeper hip feeling (stick in the belt video). Making sure the left hip goes straight down to keep everything steady. Practice this by making a lot of slow rehearsal backswing.
The compensations that occur after the stuff I mentioned. The pivot leads to the elbows pulling apart, gets the right wrist flat, left wrist is too cupped, shaft gets steep coming down, weight probably doesn't get forward enough and you kind of "scoop it" at impact.
Basically this position here on the downswing is causing you to shank it.
Overall pivot is going to feel less around and more up and down. Meaning the hips and shoulders will be working more like teeter totter, less like a carousel.
You also have a tendency to load the wrist cock early, this gets the club head in and lowers the handle. When this happens the head goes down.
What you want to start and feel is that the swing starts by the left hip/left shoulder going straight down and that the wrists are less active. Might feel more "one piece". The bending of the left side helps the hands and handle ascend (as does the rear arm bending but that's not something you need to think about).
I would recommend two drills. One is to have your head against something, door jam, poll, tree, put a piece of tape on a mirror and make slow backswing keeping the left side of your head against the wall. The head can rotate but you want the head to stay in contact with the wall. Take note of what you have to feel to accomplish this, that will be your swing thought. This will also help the takeaway with the wrist piece.
Another good drill, Dave and Erik are explaining it for the downswing, it can also be used for the takeaway. Place a ball 1 1/2 feet behind the ball you're hitting and don't hit the second ball on the takeaway. This is going to be very difficult at first, again slow swings using the same pivot feel as you were doing with your head against an object.
This will probably be something you work on for a while. Won't be "fixed" with a few range sessions. Again I encourage you to practice the motion slowly, you'll see the picture change sooner than if you only did full speed swings.
Also couple things I forgot to include with the set-up.
- Widen the stance a couple inches
- Turn both feet out about 10 more degrees.
They should when you are moving back toward the ball in the down swing. Your right elbow should be trying to move closer to your left and out in front of your torso. But, I believe Mike states that the cause is the back swing. So work on that and don't worry about the elbows at this time.
One stretch/exercise that will help shoulder/hip turn was posted by @Foursum Golf in the thread below. It is number 4 on the list. This is a great stretch/strengthening exercise that help improve your shoulder turn and strengthen your torso at the hips. I do this at least 3 times a week, 3 to 5 sets, and I also use it as part of my warm up. It really frees up the hips and shoulders and is wicked easy to do, as we say in Boston.
Pulling apart means the distance between the elbows increases. Compare these two pic, note the elbow locations and shaft alignments. Your elbows pull apart and the right is above the left at A5, on the left, elbows are close to level with each other.