I have recently install Zorin17 Core.1 to my Lenovo Think-Centre machine. I installed Firefox and DuckDuckGo for VPN tracking protection, not that these were any source of a problem. Knowing that in needed to I downloaded G-Streamer, and the Ubuntu Restricted Codecs set. and of course the DW-Helper extension, and its companion app thinking I would be able to capture videos off the web, no such luck.

When I downloaded, trying the download anywhere, to a folder, save and convert, pretty near all valid options to get playable files for VLC or Gnome-Videos. That was a total failure for me. I kept getting an error message.

'File could not be loaded, no file found. Could not create a GL context.'

But, looking with Files at the folders, there was data often in the hundreds of Mb range. Head-scratcher extraordinaire!

I did see in another forum that the 'G-Streamer Bad Plug-in' codec set would do the job, and it did!

However, a direct attempt using SUDO and 'snap' failed miserably, missing dependencies.
My rescue came in the form of a CODEC Manager in the Gnome APPS Software Installer GUI.

G-Streamer 'BAD' is installed and DW-Helper now works just fine.

Jepethiel, Australia