A small correction to this part of the article:
The open-source nv driver does have XVideo support, or at least it has for GeForce 4 series and older cards. XVideo probably works on newer cards too, but I haven't personally used them.
On the NVIDIA side but in open-source form, there are the nv and Nouveau drivers. The "NV" driver is officially maintained by NVIDIA, but it's bound to 2D support without any X-Video support and code-wise it's not very pretty. While this 2D driver is lacking, it is updated to support new NVIDIA hardware and is open-source so it ships with most all desktop Linux distributions.