In the US, phone data is expensive. But with Xfinity Mobile, it isn’t. In fact, Xfinity Mobile is a new carrier that was designed to help phone users save a lot of money on data by connecting to any one of its 18 million WiFi hotspots.

To show phone users how much they spend on data, we turned six-second pre-roll ads into price tags. So before a basketball highlight video, for example, we ran a basketball-themed ad with the real dollars-and-cents cost to stream the video. Same for makeup tutorials, game reviews, movie trailers, gadget-unboxing videos, music videos—well, every YouTube video became an ad for Xfinity Mobile.