I've read this story a few years ago. I don't think there's a conspiracy/secret advertisement: someone watched the same video as you and decided to link the text version.
To the dead comment, since it was killed right before I could finish and I can't reply there anymore (since I think a question deserves an answer):
I suspect the video you say was this one.[1] If so, you might have noticed in the description Nick Bostrom is the original author, or might have noticed the credits at the end. CGP Grey, the narrator of the video, is a fairly famous youtube personality, and have been on a sort of crusade against death and ageing lately with a few videos.
I think it's more likely that it was posted here because of CGP Grey's video bring some new (or more recent) popularity to it.
