Well, there are a few things to consider. Right now the 430 would offer you acceleration on the most applications and as well is probably using the more mature vdpau which sees more development then other api's at present. The intel HD is a work in progress and does have a few issues like not being able to give a true 24000/1001 frame rate which ends up displaying duplicate frame every once and a while. There isn't much in encoding support utilizing vdpau/opencl yet in linux. Nvidia also allows for proper colorspace playback with being able to limit from 16-235 instead of the DVI scale of 0-255. There are also advanced post processing capabilities found on the nvidia card such as hardware scaling.
The only real difference is that the OEM 430 may have a larger amount of memory on it. The trade off is that the memory is usually slower as well as consume more power. You would be better served getting the end user version as it would save on power and that extra memory wouldn't be utilized at all for video playback.
Good point, the memory shouldn't be faster, & the extra amt is only advantageous* for gaming.
And that's not the point of this card, I'll be buying another discrete mid-range later (GTX560ti or HD6950) for that purpose.
Any GT_430 make/model you like?