Simple fix for this. When running any application that is either using DirectFB or VDPAU, you may find the following error:
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied)
this is caused by your user account not having access to the video group. Without this access, you have no permissions to access the Nvidia card.
Solution:
Add your username to the video group. Open up a terminal, and run this:
sudo usermod -a -G video username
changing ‘username’ to your actual username. Reboot and all should be well. If you are also a Boxee user like myself then you will find it has the added bonus of boxee no longer crashing when trying to use VDPAU.
