Slight correction from me writing about the cinematography of 12.12′s promo. *yawns* Sam and Mary are the C-Plot, not the A-Plot. The A-Plot is Kelly and Rosemary’s baby right now which... yeah, even saying it out loud holds some weight but anyway, I wrote that when I was really tired and when I re-read it, I was like “wait, no... damnit, Past Me.” Sorry if it was confusing to anyone who noticed. To clarify. A-Plot = overarching plot of the season or whatever. B-Plot= secondary overarching plot. Usually a romance or whatever an important relationship in the show is. Usually bounces around between characters and their current relationships. In SPN it’s usually either destiel or Sam and Dean’s codependency. S12 also has Mary’s relationship with the boys thrown in and a few other ones. Basically B-Plot = relationships in shows like SPN, usually. C-Plot= This is the plot of the specific episode. It’s really obvious in MoTW episodes. There is a thing, investigate and probably defeat thing. The C-Plot is supposed to mirror the A and/or B plots to answer whatever questions with them were proposed at the beginning of the episode. So like... in 12.10: Was Cas’ decision justified? Should he think about his actions more thoroughly? What’s with Dean and Cas? What will happen when they find Kelly? By episode end, the plot of the specific episode conveniently answers or addresses those questions.
^These are specific to tv dramas and similar, not sitcoms so much. You can find this sort of structure in similar shows like Burn Notice, White Collar, The Flash, Bones, etc. It’s also pretty true for more serial shows like Jessica Jones and Stranger Things. Watch some later Bones episodes if you want to see a really obvious version of this structure. It’s not bad, it’s just noticeable. These structures are tools, after all. They have to cram a lot of info into about 42 minutes and be in keeping with the restrictive 5-6 act structure of tv. Unless you are a Netflix show (and even if you are), the structure is kind of necessary a lot of the time.
The rest of that breakdown should be basically accurate minus some grammatical errors... at least in terms of general theory. I can’t guarantee the breakdown is correct intention-wise since I’m not part of production but it’s in line with the rules of film anyway.