If you're unfamiliar with Minecraft, the build he's showcasing isn't actually advanced when it comes to building. Building in Minecraft is almost an art form, and many techniques have been developed over the years. This is because you have limited control over what you want to express: you are operating at a block granularity (more or less) and a limited number of block types that give blocks different textures.
A tech savvy teen could probably write a Java mod that generates something similar to what he's done, even prior to LLMs. An LLM could take a Google Streets feed of NY and replicate it in-game, etc.
And he wouldn't care! The thing he's made is his own, made under his own constraints, shaped by his own mind.
Perhaps a lesson of meaning in the LLM era?