The main limitation is the 1 gigabit network. It can push out 260 3megabit streams or 50 15megabit streams at the most.

That's already an enormous amount of concurrent viewers that covers 99% of content on youtube.

To achieve this, you can't be wasting processing power anywhere, a straight copy to network from pre encoded files, no live transcoding.

No scripting, no encryption either. If you really need that, which you almost certainly don't, then install a recerse proxy on your openwrt router.

Now, if you want to scale, which almost no video really needs, then you'll send the client a script. The client is a source of inifinite scaling, compute and bandwidth.

Each client just needs to rebroadcast two streams of the file.

As excess clients connect, you tell them to get the stream from the stun/turn server. This punches through both sides of the nat. And puts two clients in communication. First client sends its copies of the received stream chunks, with preference from the beginning of the file. One client can get the stream from multiple other client and once it has a few stream chunks in the cache it can serve them to new clients.

It doesn't take many doublings before you have more bandwidth than the whole internet. All the logic for organisation, hash checking, stream block ordering etc etc is a small text file from the server, signed by the server's certificate. It runs entirely inside the client's browser.