Solving the Salix 'h.264' codec issue...

As nothing seems to work with the onboard codec installer, and even though it reports as 'installed' in the Gslapt GUI manager, I went to 'Flathub' and installed their 'VokoScreen' to solve the problem. Also, a nice GUI rendition of 'yt-dlp' by way of "Video Downloader". And, as alternative to "Vokoscreen", a nice little screenrecorder called "Blue Recorder" too!
And a peek at 'Cinnamon-Spices'; some great gtk themes that can be uses for Xfce as well as their intended Cinnamon DE.
Music by G67. Check his music on "Bandcamp" by linking from his YouTube channel at, https://www.youtube.com/channel/UCObhJy16Sa1FOTXxgF9LY-Q .
Best wishes, stay safe....