We present an exploratory study of science communication via online video through various UK-based YouTube science content providers. We interviewed five people responsible for eight of the most viewed and subscribed professionally generated content channels. The study reveals that the immense potential of online video as a science communication tool is widely acknowledged, especially regarding the possibility of establishing a dialogue with the audience and of experimenting with different formats. It also shows that some online video channels fully exploit this potential whilst others focus on providing a supplementary platform for other kinds of science communication, such as print or TV