You can't come into my print shop and print Nazi literature. Could you print it yourself? Sure. So I'm not preventing you from printing it - I'm preventing you from printing it on my equipment.
It is censorship, it's just that not all censorship is bad, and people should care more about the details than that the definition fits for a word they have knee-jerk reactions to.
The parent and the government ones are similar because the censored individual can’t easily switch government or switch parents.
(And when the social media platform (google) owns not just the video site but also the search engine and the browser - it starts to move closer to the government/parent example.)
We traditionally grant children less rights (at least as far as self-determination) than adults, so this aspect is really in keeping with broader cultural norms.
And sure, the google.com/YT/chrome empire does move closer to the government example, but how much closer is a matter of some considerable debate. I'd argue not by much, but I know others would disagree.
You can't come into my print shop and print Nazi literature. Could you print it yourself? Sure. So I'm not preventing you from printing it - I'm preventing you from printing it on my equipment.
I.E - No, that's not censorship.