YouTube has finally updated the iOS version of its app to be able to playback vertical videos correctly. This update was issued to the Android app two and a half years ago but for some reason never came to iOS until now. Bye bye, black bars. 👋Now the YouTube player on iOS will automatically adapt to the shape of the video you're viewing! pic.twitter.com/4jzJ6nPj4G Team YouTube (@TeamYouTube) December 19, 2017 With this, users will be able to watch a vertically shot video in the correct aspect ratio. Previously, going fullscreen on a vertical video played it in landscape...
Source: https://www.gsmarena.com/youtube_app_for_ios_now_plays_vertical_videos_correctly-news-28830.php