Well, you're getting ideas from all over the map, literally! How typical of the Internet, eh?
In any case, after watching your video clip again, I stand by my suggestion that your boots are too upright. No single indicators are ever sufficient in themselves, and all "rules of thumb" can be broken, but if you look closely, you will see that your back and spine are almost always tipped forward more--often significantly more--than your shins. It is true in all phases of your turns, and increases (as it should) as you flex more deeply. I realize that you have described your intent as "trying to keep my ankle extended - on the gas pedel feeling the back of my boot. I'm rounding my back more than usual with arms further forward to try and keep in balance fore-aft,"
so you could be creating these positions with your movements. But it is quite consistent, and remains even on the occasions when you were actually pressing forward on your boot tongues, so I am still suspicious of your fore-aft boot setup.
If you look at the following diagram, you will see that you resemble the skier in row B, in yellow:
In the first column, all three skiers are balanced over the same spot underfoot, but the "B" and "C" skiers must contort their upper bodies somewhat to compensate for too upright (B) and too forward (C) boots. No big deal, in some ways--they're all balanced, after all. The real problem arises when they flex deeply, which causes "B" to lose balance aft--or extend tall, which causes "C" to lose balance forward.
Of course, these problems become more severe the snugger and stiffer the boot. With softer or looser-fitting boots, shin angle at any moment is more a function of your movements than of boot setup.
If your boots are, in fact, too upright, solutions include tipping the cuffs more forward or placing shims on the calf sections of the inner boots (which you can experiment with by stuffing in a trail map or two, as I suggested above). Because these changes increase the flexion (dorsiflexion) of your ankle, they may not be the best solution, depending on your range of dorsiflexion. For what it's worth, lowering the ramp angle inside your boot, as some have suggested, would worsen this problem (if it is a problem) by further increasing your ankle flexion. But if you have sufficient range of motion, shimming the cuff or increasing its forward lean might be the ideal fix.
Another solution--and the preferred one if your boots are set up properly internally--would be to increase the "delta angle" of your boot--in other words, tipping your entire boot forward by lifting the heel of the boot. This can involve lifter plates under the heels (the opposite of the "gas pedal" lifts under the toe of the boot), or lifts under the heel pieces of your bindings (if possible). Binding choice itself can be a factor here, as some bindings have greater delta angles built in than others.
Internal ramp angle alone does not directly affect the angle of your shins, but it can contribute in some ways. If you have large or low calf muscles, lowering the ramp angle--which lowers your leg in the boot--will place that calf muscle lower in the boot cuff, where it effectively acts like the shims or trail maps I've suggested above (and can add problems, again, if you have a limited range of dorsiflexion). If your dorsiflexion is severely limited, lowering the ramp angle can have the opposite effect--making your shins more upright simply because your ankles cannot flex forward sufficiently anymore. In extreme cases, you might not even be able to get your heel all the way to the bottom of your boot.
Anyway, I'll repeat that boot fitting is a complex science, as well as a black art. Our boot specialists here at EpicSki have far more experience and expertise in dealing with the intricacies of boots than I have, so again, I encourage you to raise the question in the Boot Fitter forum.
If the posture I've described is truly the result of your intentional efforts to press back on your boot cuffs, then I'll just suggest that you continue to experiment with your technique and your fore-aft balancing movements. But I'm not seeing it....