It's none of your business to scold people based on whether they watched the video or not or "read before commenting", even less to say things like "or you watched and listened but didn't think".
From the HN guidelines: "Please don't insinuate that someone hasn't read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that.".
It's very probable and totally OK that the parent didn't watch the video. Or that they watched it but skipped around most parts. It's a 50+ minute video, and it's not required to watch it in full for participating in this HN discussion.
People often get into the discussion inspired only by the title of the submission (which serves as a topic for the thread) and not the content in the linked article or video. That's just as well -- more often their contributions, even without having seen the article, can be way more informative and intelligence than what's in the article. And yes, sometimes they can even repeat what's already said there.
I'm letting you know your mistake so that you can avoid being downvoted next time.