I may be a little late for this, but I took a crack at this myself.
Z: It appears I was somewhat late for the show.
Z: I wanted to try you out myself, puny Gattsu.
Z: But I don't need the Hawks to become human and defeat you.
And post-fight...
Z: You've gotten stronger, branded one. Impressive.
G: What's stopping you? I'm still alive!
Z: Hah... That is enough for today. We both have other things to do for now.
Z: Before you and I can savor the sweet flesh of death, we must remove the small bones which impede us.
G: What?
Z: You better hurry. That branded girl's in trouble.
G: No...
Z: *laughs*
G: Casca...
As for the bone line, this is the JP version of that line, transcribed from the 2nd video:
「小骨が喉につかえた者同士では心おきなく死地を味わうことは叶わぬわ」
小骨/"small bone" is the first word, which is probably where they got it from.