Openelec does not support WMV codec and hevc HD (1920x1080) resolution has a problem with the buffer. Test done on a version 6.95.1 and older 03/09/2016.
I build it just few hours ago, although I pulled new upstream updates and fixed them, but nothing wrong with btrfs. This systemd issue was fixed long time ago. Make sure you have latest code, delete build folder and try again.