The news article is a poor summary of a YouTube video. If you just care to see the door being opened, it's around 5:13 https://youtu.be/EmqFoojMeD8 but the video itself is more interesting than that.
Sorry for the vagueness. Pannenkoek is like the authority on weird Mario 64 quirks, and makes excellent videos. As soon as you see that name, there's no need to keep reading -- just go watch the video.
Like, this article could have been one sentence: "New Pannenkoek vid just dropped: [link]"