I have similar problem.
When whatcing DVB-T in Kaffeine (0.8 whivh didn't use VDPAU, and 1pre3 which uses VDPAU) and VLC, artifacts occur in picture, and disturbance in sound too.
I have Nvidia G105M in Acer Extensa 5635G with GM45 Express chipset.
The TV card is AverMedia Volar X which workes perfectly on notebook with Intel graphics.
Here's the link with video recorded by Kaffeine, which shows all the problems:
There's photo's in attatchment which reprezent problem.