You said it! Those are the conditions that are the hardest for everyone. I doubt you'll find a skier on this forum who doesn't consider dense soft snow to be a challenge.
It's always the same story--what we need to develop is turning from ski performance, from bending the skis so that they follow an arc. Pivoty, skiddy, side-slippy stuff works OK on mellow groomed or skier-packed snow, but it breaks down in most other conditions. Get into that dense snow that the skis sink into, and the skis just won't tolerate much in the way of attempts to displace the tails. If you don't develop edge angles, then yeah, you'll go straight, or close to it. So instead we have to get carvy. Maybe when we're not on firm snow, carving isn't technically the word for it, but it relies upon the same mechanics. Develop solid carving skills for a variety of turn sizes on groomed snow, and it will translate into dependable ability to ski in many conditions--Sierra cement, true ice, wind buff, sastrugi, breakable crust, chicken heads.
The snow in your video segments wasn't whisper light powder. Don't get me wrong, it looked like big fun, but it was the kind of snow that clearly pushed back at you.
