Hey alexz, just wanted to pop in here real quick before I head to work. I do notice an improvement from your first video to the next. One thing that has remained largely the same though is a bit of "stifness" or limited range of motion in your upper body---specifically your pelvis and rib cage, especially in the transverse and frontal planes.
In addition to the many excellent suggestions above, I suggest spending time OFF the hill working on "de-coupling" your body segments and accompanying joints. In human movement, to include skiing, when one segment or limb moves one way, others must move in the opposite direction in order to keep the center of gravity within the base of support, be that one leg or 2. So things to work on would include indoor, preferably barefooted, "excercises" such as shifting your pelvis laterally to the left (which should place most of your weight in that left foot) while the spine and rib cage shift right to counter balance. Repeat for the other side. Do you find that one side is limited versus the other? Another good one is the try "side flexing" the ribcage only. Stand with both feet equally weighted and see if you can flex just the rib cage to the left and right (laterally). Try NOT to shift the pelvis to the left or right when you do this...just try and isolate the rib cage. You should feel the right obliques lengthen and the left obliques shorten when you side flex your ribcage to the left for instance. Again, is one side more difficult/painful than the other? Can you decouple the ribcage from the pelvis on this way? Yet one more to try is standing with both feet equally weighted again, but this time rotate the pelvis both left and right, deliberately yet not forcing too hard. This will shift the weight in your feet---as your rotate right, the weight will go to the right foot and vice versa. Again, decoupling is key here! As the pelvis rotates, try and keep your rib cage facing straight ahead! Can you do this? Is one side more difficult than the other? These and other movements are very important in everyday gait and also in skiing---the idea that one body segment to opposes another in movement.
Right now I see a decreased ability to move in this regard in your skiing, which could make implementing many of the suggestions you are receiving difficult. Fwiw, I coach at lookout pass Idaho, and work with many of our instructors. I notice you are in the pnw? If so, and you are ever out this way, look me up and we can go into more detail...
Josh Christopherson (alpine L3) aka,
zenny