The founding team [of Dropbox] was made up of engineers, as the product demanded significant technical expertise to build … the founders wanted feedback from customers about what really mattered to them … The challenge was that it was impossible to demonstrate the working software in a prototype form. The product required that they overcome significant technical hurdles … he made a video. The video is banal, a simple three minute demonstration of the technology as it is meant to work … Drew recounted, ‘It drove hundreds of thousands of people to the website. Our beta waiting list went from 5,000 people to 75,000 people literally overnight. It totally blew us away.” … In this case, the video was the minimum viable product.
Eric Ries, Lean Startup, (p. 97-99)