Think of it like this - if you go to a site and you know they offer accounting software, that doesnt mean you KNOW their software. You dont know how good it is, or how bad.

If you want to keep it simple, at least inform your users with your video without hiding it - ala Dropbox.

I think you need to make a much bigger effort to win your customers - an empty frontpage with just a sign up/login form will lose you a lot of potential customers. Remember, you're not Facebook yet.