I can't take my eyes off of Jerry Santos's right hand. He seems to curl his fingers up into his palm on his free stroke. And his thumb doesn't have that double jointed look like some of the Hawaiian masters.
Yeah Bing, Sarah and I watched him close up like hawks when we watched him LIVE. 5 feet away. We thought he might be actually *pushing* the strings instead of plucking. He is doing something very strange.
It looks to me like a one finger up-strum with the other two plucking high notes. Although, I also see nearly the same stroke sometimes with the other fingers too. I have seen others use what I will call a "stiff thumb" where most of the thumb is not flared out, but not very often. I would not teach anyone this way but it is an interesting technique and it obviously works well.