Mario Kart TV
From the Super Mario Wiki
Mario Kart TV is the fictional broadcasting system in Mario Kart 8, and the successor to the Mario Kart Channel in Mario Kart Wii. Within the game, the Mario Kart TV feature integrates with Miiverse, allowing players to view and share replay videos of races, which others from around the world can then watch and leave comments on. Players can view highlight reels at any time by choosing the View Highlight Reel option after a race/battle or from the Mario Kart TV menu. While viewing, players can edit their own replay videos by using various options, including slow motion, rewinding, and fast-forwarding, as well as changing the focus of the video to include specific players and actions, as well as the duration of the video. Players can also favorite up to six of their own replays. The videos can also be uploaded to YouTube, if the player has a Google/YouTube account, though they cannot be longer than sixty seconds.
An accompanying web app was also released on May 28, 2014, which allows users to find and view shared highlights posted to Mario Kart TV and YouTube. Users who log in with their Nintendo Network ID are also able to find things that are specific to them. On March 8, 2016, it was announced that the portal site would be closed on April 4.
As of November 7, 2017, it is no longer possible to upload Mario Kart 8 highlight reels onto YouTube, due to the termination of the Miiverse service.
Outside of the Mario Kart series, a Mario Kart TV patch appears on the front of the racing outfit in Super Mario Odyssey, and multiple Mario Kart TV banners appear alongside the Mario Motors and Burning DK banners in the race track area of the World of Light in Super Smash Bros. Ultimate.