Most CDNs have services for that but also that stuff matters much less if you’re not Netflix or YouTube. A basic HTML5 video tag has better UI than half of the complicated players, H.264 at phone and desktop sizes will cover almost everyone, and you’ll be fine for most businesses, conferences, etc. You need to have a LOT of traffic before the money you’re paying for bandwidth is greater than the cost of screwing around with complex infrastructure, and unless you’re streaming live events at high resolution having a CDN serving cached content is going to be faster than messing around with dynamic quality or trying to provide dozens of codec / resolution / quality permutations.
- the different formats because browsers support different stuff
- different qualities because you have to respect bandwidth visitors' bandwidth
- dynamic / adaptative quality
- CSP stuff
- nice UI for the video
etc.
At this point, PeerTube handles all this for you and it's easy to setup.