As of now and when I first saw the post appear on the sidebar, it is/was invisible on the main page and visible only through the sidebar.
Yup.
It's worth noting in general that the 'main page' is actually the 'promoted' page, which requires an admin to move you there. But you're right, the article is also not visible on the 'new' page either.
http://vimeo.com/22099396
What do people think of this, from a Bayesian perspective?
It is a talk given to the Oxford Transhumanists. Their previous speaker was Eliezer Yudkowsky. Audio version and past talks here: http://groupspaces.com/oxfordtranshumanists/pages/past-talks