We are also changing how remote playback works for streaming personal media (that is, playback when not on the same local network as the server). The reality is that we need more resources to continue putting forth the best personal media experience, and as a result, we will no longer offer remote playback as a free feature. This—alongside the new Plex Pass pricing—will help provide those resources. This change will apply to the future release of our new Plex experience for mobile and other platforms.
If I reverse proxy does the video stream itself travel via the proxy too?
In case this helps as a reference point, I use a $5 digital ocean droplet as my Plex and Jellyfin reverse proxy and it seems to handle the traffic of 3-5 simultaneous streams just fine. I use Haproxy in tcp mode (so no http interpreting, just passing packets) in an attempt to keep the CPU load minimal and just make it a pure I/O task.
Yeah, the reverse proxy will need to be able to handle the network bandwidth of your video stream too.
https://en.wikipedia.org/wiki/Reverse_proxy