I was wondering too. His series of videos on YouTube from A9 on algorithms is excellent and has some very beautiful code but you have to work through the series to fully appreciate it.

It's from a user which seems to have had their comments killed immediately. I vouched for it so it should be fine now.

If you look at the comment history, it appears that there is a ban on almost all of the comments, which suggests an action by moderators: https://news.ycombinator.com/threads?id=wiineeth