This is the link to a free trial video: https://plus.rtl.de/video-tv/serien/die-unvermittelbaren-mit-martin-ruetter-882892/staffel-2-930427/episode-6-das-grosse-wiedersehen-932203
The browser log shows a bunch of request for different .m4s files. I assume the premium stuff would behave the same but I would like to know if I can rip that before I go for a trial version
Try yt-dlp.
I was surprised how much websites besides yt were supported.
I downloaded stuff from NHK (japanese broadcaster) and they listed pages lile ARD and ZDF.
Might be worth to look if they support your page :)