This is covered in the blog post: >With one major exception — iCloud Keychain, which I’ll discuss below — iCloud fails the mud puddle test. That’s because most

This is covered in the blog post: >With one major exception — iCloud Keychain, which I’ll discuss below — iCloud fails the mud puddle test. That’s because most Apple files are not end-to-end encrypted. The blog post is saying that iCloud backups are not protect from Apple, except keychain backups. So your files, messages, etc are not protected from Apple. And the video you posted seems to only be about keychain backups.