> it’s against the terms of service to use it for video
It for any large files. They want to limit bandwidth usage but not blanket limit everyone. One user using Plex of Jellyfin probably doesn't move the needle.
Yes and that's what people are criticizing - it's just an arbitrary and thus very bad rule. Completely unrelated to CloudFlare, I streamed a single TV series from a friend's plex account 1-2y ago, that's less traffic than some of my friends use in 2 weeks.
I'm not saying they can't have that rule, it's their infra - I'm just saying that "a boatload of bandwidth" can be anything, depending on who you ask.