You know we are not big fans of vertical videos, and up until lately, google were not a big fan of this either, noting camera users to flip the phone when shooting vertical video.
They also ‘made’ the youtube app play vertical video on roughly half the screen. I am not sure if this was a bug or a feature, but it is about to change.
Android Police reports that google are finally caving in and the new version of mobile youtube (Android | iOS) will enable playing a vertical youtube on a full screen when the phone is held vertically.
If you wanna test it here is a link filled with vertical videos that you can open on the youtube app.
This ‘feature’ is not available to iOS just yet, but it will probably be there soon enough.