MONTREAL — Quebecor Inc.’s Videotron has launched a new app for Apple Inc.’s smartwatch that the company hopes will increase discoverability of channels available though its cable packages and appeal to early tech adopters. The app, called “Illico for Apple watch,” allows the users to shuffle through TV channels by choosing a category, such as children’s programming, sports or music. The app then communicates with the set-top box to cycle through all the channels that fall in that category. That function works only with live channels, but the app can also...