@fabian Is that your kid in the orange pants?  Slap a gopro on his helmet or tell him to get out the way!  Just joking...  but it is hard to see what you're doing from such a distance.

I did say I would analyze any video posted to carvers' connection last spring and I'm trying to catch up this week so here goes...

Overall your body position is good, though I do see some clamshelling, where you're bending over at the hips instead of driving forward into the turn with them.  But I'm inclined to think that what's really holding you back is the board.

I rode a couple of Koruas last season.  Superlight and playful in the powder but they behaved weird on the groomers.  They don't really lock into a carve and I had trouble keeping my lines thin, even on green terrain like in your vid.  After some efforts without satisfying carves, I just started kicking off into the side hits, which is where these boards really shine.  The overall shape with high taper and low effective edge length just doesn't really suit pencil line carves, despite the name of the board.  These are better for slashing turns.

What I see in your initiation is that the board wants to slarve into the turn, and that was exactly my experience.  I couldn't just tip it up on edge and let it guide me through the carve; it didn't like the high edge angulation and it was too short and soft to hold any real edge pressure.  Even in the fresh powder I struggled to get clean fast turns.

If you have a second look at the Yearning For Turning series on YouTube, you may see what I see: many single turns edited together ( a tell tale sign that they're not linking carves) and the riders bending low and  working hard to compensate for the slarviness of the boards when they do link turns.  Notice also the big noses flapping around when they're going fast?  That's chatter, and it takes very strong riders like these to control chatter and keep the edge in the snow.

Just one man's opinion, but I think you will do much better on a different board.