I've never managed to post a comment with a URL that printed off of YouTube. It's such a huge spam magnet, I don't completely blame them. Maybe direct people to

I've never managed to post a comment with a URL that printed off of YouTube. It's such a huge spam magnet, I don't completely blame them. Maybe direct people to "Misconceptions about the universe - Hubble sphere on the physics stackexchange", or just some search terms to get people there.