All of these costs are much higher than anyone actually estimates as people incorrectly valued them while YouTube arbitrages the real value in this.
We created an alternative to YouTube for those who have discovered the real value of these costs at Swarmify[1], but there are other options as well depending on needs/wants.[2][3]
[1] https://swarmify.com/ - No code/low code easy YouTube migration option
[2] https://mux.com/ - API based option
[3] https://vdocipher.com/ - Enterprise DRM option
You always maintain that source video file and you can easily switch to another provider. You don't actually upload to us at all. You insert our javascript snippet and everything else happens magically behind the scenes.
You're going to run into transmission problems waaaay before that.
Torrent streaming has a lot of scaling issues that you've just been lucky enough to avoid. A new torrent will have issues with its initial seeding. A new torrent is limited to the seed bandwidth of whatever seeds have the complete file. The initial members of a swarm can't help each other because they're all downloading the file sequentially so can't really share with one another. They only increase seed bandwidth to subsequent participants in a swarm and only so long as they seed the content.
In the traditional BT model swarm participants download blocks out of order so they can share them with peers. So even the initial members of a swarm can share with one another. Streaming requiring blocks be received in sequential order breaks that peer amplification.
With torrent streaming unpopular content and new content can easily stall or just never begin playback. At a small scale torrent streaming is workable but it quickly starts requiring a lot of infrastructure costs. Long tail content on BitTorrent is virtually impossible to find as popularity required for availability.
Sure, you could do something like you mentioned, but doing this for every single video is not likely to go well. But very clever! And helpful, I'm sure. Not a true solution most of the time.
I do very much enjoy the Chrome side-scrolling dinosaur game that appears when I'm offline, but I don't enjoy it more than once every few weeks :)
Reliable Bandwidth isn't cheap.