OK,
after I had now 3 or 4 installations and always some flaws or "forgotten gems" to take into account, here is my best shot for a working streaming environment with Chromium (the focus here is on 'ungoogled-chromium', as THIS version was the only one, working with Netflix streaming under GhostBSD):

  • Install ports via sudo pkg install ports tog. with sudo pkg install -g 'GhostBSD*-dev' to avoid poss. errors when compiling stuff, that "OSVERSION" is missing, or similar messages!
  • install newest version of Ungoogled-Chromium, best from software-station
  • then (sudo) pkg install foreign-cdm
  • then install from ports: linux-widevine newest version (/usr/ports/www/linux-widevine-cdm)
  • set link: 'cp -r /usr/local/share/chromium/WidevineCdm' (only comment: "pointing to") '/usr/local/share/ungoogled-chromium/' > this shd create an add. WidevineCdm in this folder structure
  • leave only ungoogled-chromium as chromium browser to avoid problems
  • restart machine to get installation of modules active
    Thanks to @Q-Pa for some easier explained steps, but let me add some checks or adjustments, that might work better for DRM-streaming, if for ex. Netflix still says: sorry, a problem occured.... ;-)
  • check in Chrome/Chromium via URL: chrome://components , if the actual module is found by browser, shd be in lower part of that table under ' Widevine Content Decryption Module' and something of version 4.10.28xx or later
  • if it s there, possibly an add. entry in URL: chrome://flags with activating or enabling #cdm-storage-database and # cdm-storage-data - but I have a feeling, with better cdm-support now in newer chromium versions, this has been dropped in browser settings...
    But after a reboot and one or two starts of Netflix (Amazon prime et al) streaming shd work!!
    Have fun!! :-D