Lindsay Ellis was a very well known film critic turned cultural commentator on YouTube. And an extremely good one. She was also a vocal feminist, and attracted some intense hate because of that. She got run off of YouTube (mostly) after a sustained and vocal harassment campaign that began after she tweeted the very milquetoast review of Disney's Raya and the Last Dragon saying it was "basically a rehash of Avatar: The Last Airbender" [paraphrased]. If you're wanting to get to know her, a good place to start would be her three-part retrospective on The Hobbit (parts one, two, and three, and her lengthy series explaining different types of film criticism and lenses that can be used through which to understand film—done through the lens (pun, I assume, intended) of Michael Bay's Transformers series. Ellis's series here was called The Whole Plate.

If your question is about this community, this is Nebula, a video platform owned in a sort of co-op structure where the creators have a financial stake in the operating of the business. It's designed to give them protection from the censorship and algorithms of YouTube, and provide a better revenue stream than YouTube's advertising-based system. Sort of like a Patreon-lite, where viewers pay one subscription fee to get access to all the content on the platform. I'm not a mod of this community, but I am a mod of !notjustbikes@feddit.nl, a community dedicated to one of Nebula's other creators. And since we regularly get questions there asking what's with the paywalled links, I created a pinned post explaining it in more depth. Feel free to ask there or here if you have any more questions about that.

If the question is about this video, well, one of the reasons Ellis is such a great reviewer is the level of depth and nuance she brings to discussions. But that makes it hard to provide a meaningful TL;DR. But if I were going to try, briefly, it would be that she is criticising Southpark's frequent status quo bias and "both sides"ism. She particularly criticises its "Man bear pig" episode, which can be seen as an analogy for climate change. The episode presents the view that people who fight loudly & publicly for change against climate change are scaremongers at worst, and just annoying even if well-intentioned at best. And she draws a through-line from that into much of the right-wing thought that grew over the last two decades. She adds a lot more nuance and detail than that, including many more redeeming factors for the Southpark creators (such as the fact that their film presented almost the opposite viewpoint: that standing up for what you believe in is important), and presents the argument far more thoroughly than I could without basically writing up a transcription of the video.

That said, I will add this comment from the Reddit comments on this video (unfortunately, many Nebula videos do use Reddit as their semi-official comments section, since Nebula itself staunchly refuses to add comments), which was quite on point:

I took a screenshot of this 2014/2015ish Reddit comment, by an account marked [deleted], that I've had for over a decade now. Here's the text:

Yeah, and Manbearpig was almost ten years ago. What an idiot Al Gore was to think climate change was real.

South Park has always been fundamentally reactionary; those pushing for change are wrong no matter what change they push for. Nothing is a bigger crime to Matt and Trey than Giving a Shit. Their ideology is apathetic-libertarian; whether you're on the left or the right, if you're asking me to change my behavior, you suck.

As it stands, the political left tends to push for more change than the political right does; as it stands, Matt and Trey admit they dislike conservatives and "really fucking hate" liberals. It isn't about left or right; it's about change versus comfort. If you're trying to change something, they think you're annoying. And they think you're lame, because caring about stuff is lame.

It's the same attitude that establishes "u mad" and "butthurt" as the ultimate trump cards in internet arguments: caring is for losers, and if you become personally invested in politics you're part of the problem. Uncritical, detached acceptance of the status quo is the only morally upright posture, and those who draw a distinction between is and ought are all smug bullies, outlandish freaks, and/or closed-minded zealots.

It's a short that teaches its audience to become lazy and self-satisfied, that praises them for being uncritically accepting of their own biases, and that provides them with an endless buffet of thought-terminating cliches suitable for shutting down all manner of challenges to their comfort zones.

South Park is a place where you never have to have your assumptions challenged. It's a place where you're always right, you shouldn't bother to think, and the people asking you to change your mind are annoying busybodies and prigs who should just shut up and leave you alone.

South Park is, if you'll excuse the expression...a "safe space."