It seems like only yesterday — well it was, in fact, yesterday — that an update for the Android version of YouTube offered new support for full-screen playback of vertical videos. Today, an update to the iOS version also supports that feature. Yay.
YouTube version 10.28, posted on the App Store today, informed users of the eagerly awaited feature.
In launching the app however, the improvement may not be immediately obvious. A vertical video will still play in its narrow box at the top of the screen. I expanded it with a gesture — or tap the button on the button in the right-hand corner — and presto, the videos now look really cool.