Over the past two years I've been watching a lot of Bilibili to improve my mandarin, and I wanted to share some of the things I've noticed in no particular order.
Chinese social media has a LOT of high quality resources to study marxism and you can find in-depth analyses of various Marxist works such as das kapital. However, there is generally a greater interest in nationalism rather than marxism, which has been pointed out here before. There is also some general hostility towards Vietnam. One of the reasons for this dislike seems to be that Vietnam is supposedly cozying up to the US, and had apparently hosted an american navy ship. There isn't however much dislike towards the DPRK, and people tend to think of it as a generally happy country although perhaps a bit quirky and closed off. Of course, Chinese youth is much more interested in kpop and south korean culture overall.
There is a lot of content from Youtube that will be reuploaded directly to Bilibili. They tend to have a title prefaced with: "油管百万播放量" (Basically meaning: "this video has millions of views on Youtube"). Even some very political Youtube videos will be uploaded to Bilibili, for example, I saw someone who reuploaded a debate between Infrared haz and Vaush with Chinese subtitles. The comments pretty much said: "This is how americans debate politics? Why are they screaming so much? Why is this vaush guy pretending to be a leftist?". I've also seen some reuploaded low quality 'social credit' memes (you can find it by searching 社会信用 on Bilibili) as well as some discussion around how westerners obsess over the social credit system.
弹幕 (Dànmù) is a feature on Chinese social media that allows users to leave comments on the screen of the video itself (so you will see comments going across the screen while watching a video). At first I hated these, so I turned them off, but I've actually started to really like this feature and now I kind of wish it was on Youtube as well. (Yes I know it makes my attention span even worse, since besides just watching a heavily edited video, I'm also seeing people's reaction at the same time to keep me less bored)
I've been consuming a lot of content relating to China's space program, and I've noticed that there are a lot of people who seem to believe that the US moon landing was fake. You'll never see content creators themselves say that it was fake, but whenever the US moon landing comes up, there will always be dànmù talking about how it's faked. I do think this is a bit weird, since Chinese social media will usually remove stuff that's non-scientific, but to be fair, there has been some funny jokes coming out of this. In the comments of NASA's Chinese channel where they showed off their plans for the artemis program, the top comment was like: "This time the moon landing will feature next generation 4k photorealistic CG, with revolutionary new filming techniques and special effects that will make you truly believe that the US landed on the moon"
Criticism of the government is quite normal but it isn't comparable to the way we in the west criticize our governments. People will usually focus on criticizing specific policies or socioeconomic developments rather than the ruling government, since people are generally happy with the government as a whole. I've found people criticizing the Chinese education system, how the society is afraid of sexual education, how household debt is rising, how youth unemployment is rising, etc.
As for some of my favorite content to watch, I'll start by highlighting the building sphere of Bilibili, where people build lots of cool stuff. For example look at this sci-fi desk thing. I also found this great video that does a really great job of summarizing the science of language learning.
Also, there are so many amazing free university lectures accessible through Bilibili, covering things like Das Kapital, Machine Learning, PID control systems, and more. Maybe its just my recommended page, but Chinese social media seems to be much more obsessed with educational/science/news content rather than the cheap try not to laugh content which floods Youtube.
The Chinese have historically held learning in high esteem and it remains the case today, imparted from parent to child at all levels of society. (I am sick from hearing it nonstop growing up the, lol.)
Comes from Confucian traditions and the historical meritocratic bureaucracy. Taking the imperial exams was how one ascended the social ranks, for millennia, or maintained one's current high rank. Titles in the bureaucracy was not heritable, and every generation that fails to get a similar high level job gets demoted some ranks down, until they are relegated to commoners, oh the horror. Hence studying has always been considered the best thing to do to develop one self and one's place in society.