Edit: Currently (about two month later), it does not seem to work anymore =(
It worked on my machine with a Firefox 60.9.0esr. But at first, there were two things that hindered the playback:
- The Ad-Blocker – I had to disable it.
- The user agent setting of Firefox has to be something like “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3835.0 Safari/537.36”. This can easily be achieved with the Firefox addon User-Agent Switcher and Manager.
You also have to make sure, that the Firefox Addon “Widevine Content Decryption Module provided by Google Inc.” is installed and activated (see Watch DRM content on Firefox).
In my opinion, it is pretty silly that you have to fake your user agent in order to watch the movies. But according to the customer support this is done on purpose:
Da wir Linux nicht unterstützen ist ein funktionierender Abruf über die entsprechenden Systeme nicht vorgesehen.Reply from the “maxdome Kundenservice” on my inquiry (December 8th, 2019)