I like the idea of a nocked throwing stick. The woodland indians, Paleo period, near Harmon's Creek, used banner stones on them. The stones, when found, were thought to be gewgaws but were eventually demonstrated to be a sliding counter weight on the throwing stick that multiplied force when it rapidly slid along the stick towards the notch. I made a simple banner stone, shaped something like a butterfly with an elongated hole bored through it and placed in on my throwing stick and saw a significant increase in target penetration although it did alter throwing technique a bit. I tried one that was groves to rest the dart but my stone proved too brittle and broke on the second throw and I never got around to building another.
Neat video- What is that building you are standing in front of? Is it abandoned? - and what in the world was that chuffing noise in the distance?
It's a house that never got finished I use it to watch my house and train in that's my dog panting he has found him a girl friend and has been busy
I have one that I use rain deer antler as a banner Stone I have seen some that have a hole in them that slide down the atlatl when throwing the dart
The nock may be cut a little too deep. As you throw, the dart can swivel on the string (which is good), but the string may start pulling the end of the dart down if it doesn't separate immediately when the thrower passes vertical. Just a guess. Cool idea with the forked stick.
With a cup, the dart could have a rooster tail pointed upward , ( in stead of a nock.) as you make the arc in your throw the tail would bear the load of the push, tail of the dart would not be caught in the cup .