I've been getting this prompt whenever I play movies using Gnome MPlayer.
Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object file: No such file or directory
Today I searched for solution, and I found this:
* Open Edit -> Preferences in the GNOME Player menubar
* Select the "Player" tab
* Select "x11" for the Video Output
* Close preferences and try to open the video file again.
The problem solved.