There's a known bug in X Server 1.18.4 that is related to SDL-based video playback. It's impacting my ability to use other Ubuntu-packaged video applications such as Flowblade video editor. Flowblade's dev has assisted me isolating the issue via Black playback screen on Elementary OS 0.4/Loki (Ubuntu 16.04) & MLT 184.108.40.206; works in Shotcut.
I tried using “xorg crack pushers” team @
ppa:xorg-edgers/ppa but that almost hosed my install.
How can I update to 1.19?
(EDIT: Cross posted to eOS's Launchpad; apologies if this is discourteous.)