At this time you can be happy when having a working video editor on elementary OS.
Kdenlive from the 14.04 Repo is very outdated and has some problems. The newer builds from the ppa rely on newer dependencies and don't work on 14.04. It is also not very intuitive.
The only way I have managed to run kdenlive is by an appimage. Works like a charm. This is what I recommend.
Latest stable AppImage (17.12.0) is available here:
To install, just download the file and make it executable, ( chmod +x ) in a ...
This upgrade is handled upstream by the Ubuntu project. This Launchpad bug tracks the integration of xserver 1.19.3 into Ubuntu. There are reports of Ubuntu failing to boot with the new version of X Sever, which would line up with the problems you encountered with the exorg-edgers PPA.
It sounds like this update targets the upcoming Ubuntu 17.04, but I ...