Nvidia wants to promote NV4X generation of chips as the ones with high quality video, complete and ready for HDTV and PVR.Source: The Inquirer
High quality video will brought motion adaptive de-interlacing, high quality scaling and filtering, good old video de-blocking and integrated TV encoder.
As for HDTV, Nvidia claims Transport stream handling, HDTV output (720p, 1080p, 480p CGMS) and HDCP - High-bandwidth Digital Content Protection as well as HDMI High-Definition Multimedia Interface support.
The PVR part is the most interesting as Nvidia claims that the NV4X generation will have support for no more and no less then MPEG 1/2/4 encode and decode as well as WMV9 decode acceleration.
This means that all decoding and encoding operation previously done by software and very CPU dependant will be able to be processed on NV4X chips. We are not aware specifically how Nvidia plans to do that but it sounds promising.
NVIDIA NV4x cards to have MPEG 1,2,4 encode/decode

The Inq reports that NVIDIA's NV40 will have some additional video capabilities. It looks like that all the NV4x cards will feature these options.