For discussing entertainment like specific video games, movies, book series, TV shows, sports teams, etc. there simply isn't a good alternative to Reddit.
I hate the site and have limited the time I spend on it but there aren't good alternatives for certain communities.
I miss those forums! They were simple and fun, and each board being scoped to a specific movie/show kept all the conversations very focused.
Moviechat.org seems to be a spiritual successor, and I'm pretty sure that a lot of its initial content is archived IMDB forum posts, but it's not nearly as active.
I hate the site and have limited the time I spend on it but there aren't good alternatives for certain communities.