To become a “destination” and keep mobile viewers hooked, YouTube realized it had to fix itself, from its development platform to its AI.

The war over our eyeballs is heating up, and that’s mostly a good thing for people who like to look at screens. Just as Meerkat, Periscope, and Snapchat elbow each other in a battle over appointment viewing, and digitally native companies like Netflix and Hulu duke it out over the future of TV and movies, an old-school competitor shows up and throws down a shiny new gauntlet: Last month, HBO Now launched just in time for cord-cutters to catch the debut of the new season of Game of Thrones. There’s never before been such an abundance of quality, readily accessible television fighting for our attention.

YouTube, however, has found itself in this new golden age of video with a serious handicap: While its overall viewership was growing, most of that growth was happening across the web at large, outside of its own site and apps. That made it harder to capture eyes and ad dollars, and to appeal to cherished mobile users. When Susan Wojcicki became CEO last year, she would continue efforts to transform the way it served ads and engaged with its creators, pouring money into certain channels and promoting them heavily.