The images in VLC are correct and I have just found Spash Lite that plays the video OK but the sound comes in bursts!!
I think that will struggle with high bitrate/res h264.
In theory the 6200 does have purevideo and nvidia claim some h264 accel for it, but it looks like free players like vlc and media player classic only do dxva for more recent cards (and OS > XP for vlc).
Maybe Splash Lite is using some GPU or maybe it's just fast/efficient at software h264 (possibly by reducing the quality)- shame the sound doesn't work.
The sound issue could also be because you are running out of CPU - task manager graph will tell you.