FYI, I work for a big sports streaming company and we are doing "mABR" or multicast adaptive bitrate with some ISPs because it really is worth it. You get a sig

FYI, I work for a big sports streaming company and we are doing "mABR" or multicast adaptive bitrate with some ISPs because it really is worth it. You get a significant improvement in playback stats and the ISP gets massive traffic offload from their network. We started with one big ISP in Italy, then other ISPs saw what we were doing and asked to join in. That being said, it really is a pain in the arse to build. It's also largely proprietary solutions (yes it's multicast but getting the player to find the content isn't a standard) and it's hard for the ISP to update ALL their routers to support it (even when they want it).