missing the codec. maybe vlc?
Nah, none of the open source applications (VLC, Kodi, etc.) can use the HEVC decoder in the GTX 950/960s yet because FFMPEG doesn't have driver support (its close though):
https://devtalk.nvidia.com/default/topic/858536/hevc-h-265-support-on-linux-vdpau-/
Here is a good article of how to use LAV codecs to get the job done:
http://uk.hardware.info/reviews/589...f-this-moment-h265-on-the-gtx-960-innpractice
maybe vlc?