RC/PE1

https://vid.me/Vjpx

 

How is it looking? I know he's bouncing a little, but aside from that...

looks like you are not using your back instead you're using your abs

So his back should be straighter?

Rings are too low. Have him sit like in the final position and his arms should be nearly locked out.

Set up of this is vital. As Vncearoo said, you should set this up from the final position.

 

He's doing this more as a crunch, it's meant to be more of a hip hinge, so the final position will have a more neutral torso and open chest.

Aha. I saw once that the hinge row should be thought of as an assisted crunch; this is wrong then?

The post you are thinking of said 'assisted sit up' to help people understanding the hip hinging nature of this element.