POV JAV? Or the camera man’s personal fetish?
It's quite a mystery, and tiny-bit off-topic, and a lot to deconstruct. But here's how I think about it:
An JAV performer is extremely unlikely to perform any sex act (sucking cock, getting facial and swallow some sperm is way more than minimal definition of sexual act) unless it's part of paid work.
LUXU- is a semi-amateur category, so rules could be a bit loose.
BUT the performer was 水咲菜々美 or 宮藤さくら (multiple stage names for the same performer) she is a minor veteran active from 2012 to 2017. I very much doubt that she would perform any sex act outside of contract.
Original release date was 2016/10/21, I don't remember 2016 that much... it could be in those days the rules are a bit loose.
What you call "cameraman" is probably the director. A famous director or studio boss might be influential enough to get out-of-contract sexual service from a young girl who desperate to get better exposure and investment. BUT I highly doubt such an influential director/boss would personally show up at the filming of a LUXU- title. Also 水咲菜々美 had already years of work history as semi-pro/amateur, I just can't imagine she would do sex for any career-climbing or just-pleasure purpose.
NO MATTER WHAT, if there's any sexual interaction between a performer and a crew, (let's say an influential director wants to unload his sexual energy on the performer) it would absolutely not be filmed in a semi-professional way (third person view) or crappy way (guy receiving the blowjob himself holding his smart phone to film the action). I won't believe a third person would be present, and filming. Not even back in 2016.
My guess is it's a fake-reality scene as a bonus footage. You said it's filmed (probably) after the filming for LUXU-465, I think it's common to film for a whole day to get enough footage to edit into two or even more titles, so it's possible this "bonus" footage was released in some other titles that we are not aware of. Meaning this is not any private act and private footage, it's staged, starring a guy who is qualified as JAV male performer (at least was tested) and she was paid to perform for the camera. Was the guy also a camera man/director, it's possible, but my guess is, he's not, He's a minor/low profile male performer, or even a "juice-man".
Anyway very interesting.