Is it easier to collect emails with a membership website?

I've got an information website (custom, non-wordpress) that receives 70,000 visitors a month.
I'm thinking about creating a free membership section for the sake of collecting email addresses. I currently offer a free ebook download (in a box in the sidebar) as an incentive to subscribe to my "newsletter", but I want to replace this with a feature of free MP4 downloads of educational videos if you become a member.
Do you think membership would be a more effective strategy over the free ebook…
Is it easier to collect emails with a membership website?

See original post by Inersha