Anyone serving anything publicly should be using a CDN for binary objects like images, videos, downloads, etc. That's why CDN plugins are among the most popular downloads for WordPress.<p>If you mean "without a CDN", then as someone whose daily job is delivering millions of users high quality videos, I would ask: why would anyone do that? It's like saying "I'll dig my own fibre to the home..." Sure, you may do it if you have no choice, or you simply use an ISP.<p>CDNs distribute the load and make it more economic to deliver your content. They provide lower cost and better quality streams through more servers and higher available bandwidth.<p>Sure, you host the videos, you act as the origin, but the CDN sits in front and takes the load. You only have to worry about cache efficiency for your bandwidth. But I can say that you can serve millions of users with 10Gbps and a good CDN, which is feasible for home internet in some places.<p>For the self-hosting numbers, without a CDN, just take the average bitrate and times that by the number of concurrent users. So you are going to be looking at 6Mbps * 100 users = 600Mbps upload, plus about 10-20% overhead/margin.