WOW, I saw your message exchange in mesa/gitlab. Thank you for the effort you put into such a complicated matter! Linux, of course, is carried forward by the interests and skills of the contributors. Unfortunately, video editing, color management and other professional areas have never been developed much. Mesa is also developing very slowly, in an area where proprietary drivers are advancing at great speed. I have read that many video editing professionals would prefer Linux over Windows or macOS because of the greater simplicity and power in networking (rsync; render farm; lower risk of data loss; etc.). But so far only Blackmagic and Lightworks have tried to approach Linux, without too much effort. PS: in the comments, users point out that at the exact moment when the author of the video was talking about the lack of hardware encoding in Kdenlive, the video was showing the 4 hardware enconder options! :-)