Holy Manatee, this is confusing!
Ok. Videos showing black was not openGL3.1/EGL, it was
Totem!
But, I did put that TearFree true line into
xorg.conf.d and restarted X. Too early to tell about
plasma lockups, though.
I read that EGL is supposed to be the interface for
Wayland, so I thought I'd give it a try now.
So, I'm trying TearFree, openGL3.1 and EGL all enabled
for a few days ;-)