YouTube used to be for cat videos. How passive. Soon you'll be able to watch it and buy kitty litter. YouTube is introducing the ability to shop for products directly from its videos, a move that opens the door for new revenue as the online video site looks to turn a profit. The ads can appear on any video and will be served by Google, which will decide which videos to pair with an ad. They will be relatively unobtrusive, with a small box in the top right-hand corner appearing. Users that click will be shown a drop-down menu of products to peruse as the video plays.