YouTube is a website created for the purpose of sharing and viewing videos on the Internet.
Relevance to the Super Smash Bros. series
YouTube has played a vital role throughout the history of the Super Smash Bros. series; prior to YouTube's creation, the distribution of videos over the internet was a rather difficult process, with smashers often having to use slow, unreliable services to upload and view videos. YouTube's ability to quickly and easily view and upload videos, as well as to discuss them, almost immediately increased the distribution of gameplay videos; later developments to YouTube's services also allowed for more in-depth videos and playlists to be uploaded to the site.
Within the competitive community, YouTube acts as one of the primary places to upload tournament battles or money matches to the Internet, and for others to watch them. Friendlies between professional smashers have also been uploaded to the site, and some smashers, such as aMSa, also upload technical data and combo videos to the site.
YouTube users have also made instructional videos for aspects of the Super Smash Bros. games as to assist casual players, such as how to perform certain techniques such as wavedashing and L-canceling, in addition to game guides on how to complete game modes, such as Subspace Emissary or Break the Targets. Other miscellanies include the uploading of the music of the Super Smash Bros. series, reviews, trailers, speculative videos, and walkthroughs/Let's Plays of the Super Smash Bros. games.
With the update to version 1.1.0 in Super Smash Bros. for Wii U, it is now possible for players to upload their saved replays to their YouTube account, something that had previously been only possible at all via methods such as external cameras or various kinds of capture devices. Replays must be no more than about 3 minutes and 14 seconds in length to be uploaded (likely due to the time taken to convert the data into video format, along with taking into account upload speeds for users with slower internet access). Replays will be uploaded in 720p resolution. The upload can also have a Miiverse post made simultaneously. In version 1.1.1, the ability to trim replays into a series of clips and upload it to YouTube was added (although it is impossible to choose which clips get uploaded). Oddly, after uploading is finished and returning to the game, a message will say "Post Canceled" even though it went through. As of the discontinuation of Miiverse on November 8, 2017, uploading replays is no longer possible.
Use by Nintendo
Nintendo itself owns a YouTube channel, under the name of "Nintendo"; the channel is used to upload videos concerning developments of Nintendo consoles and games, as well as for advertisements of such ventures.
There was originally an official Super Smash Bros. YouTube channel, which uploaded all of the promotional character trailers for Super Smash Bros. 4; the channel was first named SmashbrosCh, and later renamed to Super Smash Bros. These videos are still live on YouTube, and claim to be uploaded by Super Smash Bros. However, the channel itself no longer exists, and simply redirects to one of the general Nintendo YouTube accounts.
Both the Super Smash Bros. 4 Official Site and the Super Smash Bros. Ultimate Official Site have YouTube videos embedded onto it, most of them being character reveal trailers and Direct clips pertaining to Smash.