I watched the entire video, but I timestamped the link to where I believe it matters most for any comrade that ever liked Star Trek, liberal idealistic and quasi-militaristic flaws and all, and would like to see a succinct and thorough summary of what they might have already felt, may have already inductively collected for themselves, but got it drowned out by "well the TNG gang got together by the end of Picard Season 3 so just enjoy it like a popcorn movie, 4/5" or even worse brainworms like "section 31 is based and it's just cold hard reality that such an agency would have to exist for the Federation to exist, just like in based Deep Space 9 which was totally about wars and genocidal biowarfare plots and how cool and necessary they are."
The Trek fandom site in the Lemmyverse is loaded with insufferable liberal/libertarian 
and a fair amount of Thermian Arguments that justify anything that was presented on screen as not only good, but necessary if they were done by protagonist characters, and not just the flaws, weaknesses, and (for lack of a better term) sins of characters that weren't intended to be infallible, let alone blindly emulated, no matter how cool it was when Sisko punched Q or whatever.
TL;DR: I hope comrades find value in this concluding section of a much larger video, or maybe even watch the whole thing, which I also think is worthwhile. Also, I fucking despise Section 31 apologists because they make the Lemmyverse's Trek site unbearable for me. If Kurtzman gets his way (especially with that Section 31 series he keeps jerking off about), Trek will become increasingly murderfucky gory edgy black ops obsessed bootlicking schlock with a vague and redundant nostalgia flavor.
Have you ever read the Culture novels, by Iain M. Banks? They explore a somewhat similar idea to "intelligence agencies of ~~fascist~~ post scarcity interstellar empires".
I can't remember if the contacted civilizations are ever socialist, although there's definitely a more feudal one and the overall themes may be interesting to you nonetheless.
There are more than a few passing references to contacted civilizations that are pretty primitive in terms of technology but very advanced socially. The result being that they are contacted a lot sooner than capitalist societies, which have to be subtly pushed and nudged into being less shit.
I love the shirt story, State of The Art, where they decide to use Earth as a control and not get involved at all
Oh damn, I forgot that part about "Earth being the control". That's hilarious!
My favorite one of them is Excession. I found the relationships / culture between the ship AI's so interesting and frankly, better written than many human relationships in the series overall.
It was a fun book and definitely exposes the lib brained tendencies of the Culture ruling elite (the Minds).
Look to Windward is my favourite. I love its pace. We see more day to day Culture life in that one than any other, and we also get to see the consequences of their meddling when it all goes wrong. Ziller is a great character and he is played so well by Peter Kenny in the audiobook.