If you would take the time to write a proper description of the issues you are facing you would be far more likely to get replies. What are you currently doing?
You can get more signups, sales or whatever you want visitors to do by convincing them to do it. Put yourself in your visitors' shoes. Why would I buy that or why would I give my email or subscribe to this site? If your message is weak, you'll get a weak response. You've got to answer the question in the prospect's mind: what's in it for me? You have to show the benefits. Price is not a benefit. Solving a problem and removing a pain is.
I do not mean this in a bad way just a rhetorical way, what am I signing up for? Your site doesn't really give me any idea?
Agree with gorz, i dont see WHY i should sign up. Maybe you could make it easier to sign up, meaning redesign the sign up form a bit, and require that people have to sign up before they can submit videos. It seems to me that everybody can submit videos without signing up...