I was looking for such a service for few weeks, affordable for startups. However, the 'make' experience is not so intuitive; I was often thinking what next while adding pictures, to save the library, and so on. I assume that you are working to optimize it!
Video is awesome for ads, but the cost of production is way to high for SMBs. Shakr fixes this. Its a great tool for giving SMBs the ability to compete with big brands for attention online.