Some of them do, and some of them only serve the purpose of INtK, whilst others don't at all. I'll go through and write up a description for each link, at some point, soon.

thank you, do they include a comparable "I need to know"-section in terms of topic and number of participants?
17,000 getting a kick in the stomach for no or the wrong reasons!

That's pretty close, yeah! Shoot me, but where do you start discussions on specific films?

There are already a few threads about this. My suggestion, as stated before, is this one:
https://www.themoviedb.org/
Very similar to IMDb but non-commercial. Discussions are possible for every film/TV entry.

Some of those are completely dead. You might as well as put movie forums. com up there also. It is pretty busy.

http://namethatmovie.org/
https://www.reddit.com/r/tipofmytongue/
http://film.chat/
http://www.movieforums.com/community/
https://www.imdforums.com/
https://www.themoviedb.org/talk
http://www.killermovies.com/forums/
http://area51.boardhost.com/
http://imdbreplacement.forumotion.com/
http://nytramsplace.activeboard.com/
http://s15.zetaboards.com/Colliding_Worlds/index/
http://thegotboard.com/
http://www.imdbmessageboard.com/all/
http://imdb2.freeforums.net/
http://www.famefora.com/
https://8ch.net/film/catalog.html
http://s15.zetaboards.com/IMDb_tribute_Gooey/index/
http://www.sitcomsonline.com/boards/forumdisplay.php?f=419
http://www.scifimoviezone.com/sfmzforum.shtml
but some of them have more general or more specific purposes.