I think he’s recording it for his interest
Nah. He clearly is gonna blackmail him. You didn't read it at the last panel on the chapter when they first have sex? Because I clearly can remember he had a dark aura and said some thing like "This will go around if you don't start blah blah blah tomorrow". Not the exact words (or maybe far from.what he said XD) but I'm certain he said some words that are clearly blackmailing Ryo.
I think he said it as a joke, Ryo replied in a kind of jokingly manner; but I don’t think he blackmailed him
that makes sense yeah, I still hope he doesn’t use them to blackmail Ryo :)
The seme is really bothering me. He recorded their sex and still wanna blackmail Ryo even Ryo is already showing what he feels about him. He's a case. And that's not good.