I'm running Kubuntu Vivid, and have an Nvidia 940GM card on my Inspiron laptop. When using the nvidia-346 driver, VLC plays choppy videos (video seems "pixelized" with green dots appearing).
The situation doesn't happen with the nouveau driver, nor does it happen with other players. How can I fix this? I tried different GPU accelerations and shutting it off (that's what I found after googling) but it doesn't help. I had the same problem running 14.10.