Phones are charging ~8 hours a day whilst you sleep though. And few people mind the phone seeding stuff on your home WiFi whilst charging. Many users could also spare 32gbytes for seed data too, especially if the app was smart and automatically reduced the store size before the phone started to notify you of low storage space.

If a typical user uses preertube 30 mins a day, that still gives a 16 to 1 ratio between seeding and leeching, and a 1024 to 1 data storage to data viewed ratio, meaning there is a good opportunity for a big back catalogue.