Yes but also no. the tldr is It will work, but video streaming is against CloudFlare rules. I ran this way for about 2 years with Plex just for my own use, so for about 15 hours a week on 480p and I never got my service suspended, but I’ve heard stories of others getting suspended… So just know it’s a risk
My understanding is that this clause was quietly removed from the Ts and Cs, perhaps 1 or 2 years ago. I haven’t heard of anyone getting banned for it recently.
Personally while I have Jellyfin set up through Cloudflare, it’s almost entirely run local-network only (with a local DNS entry in Pihole to connect to the domain direct when on my network) so I haven’t had any issues but probably wouldn’t trigger any unusual activity alarms in Cloudflare.