I've seen that video before. It's a KO video but I don't remember which one. If you're keen on finding the actor, they might be listed KO's actor page. Here's the link, you don't need to speak Japanese to figure it out.
https://ko-video.com/fanspace/model_list.php
Hope that help a bit. 
Oh, I see. I didn't know that. Thank you for explaining. 
Thanks for the reply. Good to know.
Thanks. Though I have not a clue how or why the math is the way stated, I'm going to assume all is right with my torrent and I can just go about my day.
Cheers,