Get ready for bigger battles over smaller screens. As TV viewership declines, especially among millennials, online video has become one of the hottest corners in media. Over the last year, several companies, in both media and tech, have rushed to compete in this emerging space. There’s a lot of speculation over what the new challengers mean for YouTube. When I’m asked about the competition, I say that it’s a good thing, to the extent that it focuses us on improving our product. The digital ad market is growing quickly, and there will be more than enough room for many successful companies.