Originally Posted by
Langball
I'm not a pilot, but I did notice that he appeared to be sitting on the thumb of his left hand (thus restricting the movement on the collective). Never seen that technique before.
He's not sitting on his thumb, he's resting his thumb on the edge of the seat. This can allow one to have more precise control of the collective position by using the fine motor skills in one's hand and finger muscles, rather than the more gross motor skills available in the arm muscles. For small changes, one just squeezes between thumb and fingers with more or less pressure. Not everyone has large enough hands and not every helicopter has the right geometry to allow this method, but it seems to be quite common.