Cinemasins is definitely a unique concept with a lot of promise. It's memorable as well, because it pulls it off in terms of presentation. Content is where Cinemasins falls down. While they do raise several legitimate points, it's lined with pedanticness that will go one of two ways: Jeremy will point out meaningless things that will mean nothing to the "average" cinema goer he claims to represent, or will show a lack of understanding of the source material.
It's also billed as a comedy, which would work if their jokes weren't so hit and miss. And when they do "hit" they'll milk an barely-funny joke for everything it's worth (SCENE DOES NOT CONTAIN A LAP DANCE AHAHAHAHAHAHXDDDD).
Not to mention the way they'll occasionally critique a cartoon for simply being a cartoon, or make fun of a movie for making use of basic storytelling techniques like narration. To some extent, it reeks of a screenwriter who's "unique and brilliant" screenplay got rejected one too many times.
Of course, like any series, they're going to have their hits. But their hits are overcrowded by their forgettable videos.