Quoted from rosh:hard to see it precisely, since can't real scrub on youtube, but seems it starts to move forward before the ball starts to drop, possible due to your pitch. I'll have to see if I can make that delay a touch shorter and see if helps that scenario without negatively impacting others.
In spite of the drastic game pitch, it looks like the ball cant quite go over the hump of the captive ball to drain out.
Ill have to check mine as it also rarely works.