This looks to me like a classic case of "I didn't enter the picket's range why did it shoot at me?"
Kodachi is predicting the movement of bandit. When the predicted bandit location is inside of kodachi's range, it aims and shoots at where bandit will be. Which is why in your video bandit can fire at kodachi from range, but also kodachi can fire at an out of range moving bandit(only when bandit is moving closer to kodachi). I had thought this might have something to do with the new fire in the direction of units gadget, but looking closer that didn't seem to have a large effect.
Also note that kodachi has some inacureacy, as well as the aimpoint being a predicted position means that by firing at a invisible floating target at the edge of range, it's possible for a projectile to fly overhead and past the max range, impacting many elmos outside of kodachi's range.
Finally, by watching the replay I do believe that 2 bandits well microed can either dissuade or kill any kodachi that wants to go through any chokepoint in redcomet. One bandit alone will half kill the kodachi when it charges head on, 2 with some spacing definately can kill a kodachi that charges headlong into them both. Just be careful that koda's riot like properties don't burn too strongly against both bandits at once.