the question says it all. I would love to install the youtube lens but I see no trace of it online.
The only clue I had was that it was a contributor of OMG Ubuntu in an article from OMG Ubuntu. It had no link.
I don't think you can. The post says "The following YouTube Lens for Unity, currently knee-high in development by a certain regular OMG! Ubuntu! contributor". Even if you get the source from their ppa and build it yourself, it might be buggy since it's still in development.
I would recommend Minitube, it's the primary Youtube app on my Natty system.