Wait what? The GP said they were not mobile-first, they were mobile-only and that’s true.
And No, what you say is not how any of the video services work. Pandemic or not, the largest selection of videos are 16:9.
Quibi bet the house on a mobile-only portrait videos In 10 minute chapters. You claim there was a market for that - but give no evidence.
There isn’t a broad market for that niche offering!