I was wondering whether Totem supports audio-video streams that use Widevine DRM.
I tried https://start-player.npo.nl/video/LI_RA1_8167349/streams?profile=dash-widevine&quality=npo&streamType=liveradio (from NPO Radio 1 - Online radio luisteren – Nieuws en Sport , that works in Firefox, of course if Yes is selected at the “Enable DRM” prompt), and it didn’t work.
I was also wondering whether some GStreamer plugin is needed
There is no Widevine support in totem.
The biggest problem here is that it is illegal to use Widevine without signing a legal contract with Google. Google has previously privately indicated that they will not offer a contract to us because we are an open source software project. That was many years ago and I think it’s time to try again, but these communications really need to be handled by lawyers to be effective, so it requires coordination and planning with GNOME Foundation. (Also, I suspect there will be some resistance to the prospect of GNOME distributing proprietary software.) I’m quite interested in this but just have not had time to pursue it thus far.