I would have thought that the point of federation is not to require centralized servers that cost a lot to operate.

But sure, something like this probably requires a fundamentally different revenue model. Maybe even the one where people donate to server operators.

centralized servers cost less to operate, that why data intensive applications centralize over time. That's division of labor. The higher the complexity the the higher degree of specialization. And a video service is very demanding.

And you need to solve the economics first because otherwise your decentralized service is simply going to centralize over time to deal with demands for a more reliable and higher quality service. (and how to compensate creators)