Some friends of mine just completed their successful Kickstarter campaign for Sunglasses with a Bottle opener - http://www.kickstarter.com/projects/2093465669/jackhawk-9000... and from the feedback that I got from them it was about the video and the outreach that they did during the campaign.

They created facebook groups, updated the kickstarter page and built a cultish following out of family and friends. They also had enough level in which people could show support and then share the link on facebook to expand their network.

But having something that solves a perceived problem, having it close to completion or "just needing the money for production" seems to work because people know that they will get the product.