The full title is actually SSDM 645 50人集團催眠2 (not sure what that translates out to)

Searching around it seems to be a japanese produced smut movie that functions on the premise of hypnotizing a crowd of 50. Haven't been able to find much out on it. Anyone more familiar?

Somebody on hypnopics archived some clips from it:
hypnopics-collective.net/...earch&cat=0&pos=0
hypnopics-collective.net/...earch&cat=0&pos=1
hypnopics-collective.net/...earch&cat=0&pos=2
hypnopics-collective.net/...earch&cat=0&pos=3
hypnopics-collective.net/...earch&cat=0&pos=4
hypnopics-collective.net/...earch&cat=0&pos=5
hypnopics-collective.net/...earch&cat=0&pos=6

Google Translate says it means "People group hypnosis" which, by your later definitions, is correct, but the grammar is poor. (it's Google Translate, I don't expect grammar)

The title you've written is 50 person group hypnosis 2. It's exactly what it says on the tin. The actual title is longer and more rambling, but it's just 50 women being hypnotized at once. That's the idea anyway. As far as I can tell the 2 isn't actually correctly placed, and this isn't the second of anything, it's the only one there is. I remember watching it a few years back, but it's probably long gone from whatever streaming site I saw it on. What exactly do you want to know about it? As long as you have that production code, the SDDM-645, you can look it up pretty easily on DMM or other sites.

i cant registration this site :/
"Your registration has been blocked by our spam filter. Please either try again or contact an administrator (admin AT hypnopics-collective.net)"

Those links don't actually go anywhere. (you copy-pasted the wrong URLs. The ones above are temporary ones.)