mplayer complains about not being able to find I checked in /usr/lib, and it’s there, but it’s a link that points to /usr/lib/vdpau/ The folder vdpau doesn’t exist.

Which package do I need to install to get this to work?

easiest answer is to open yast software manager and search for vdpau and select all (or if 64bit maybe skip 32bit ones)

I did, no dice.

do you have a nvidia graphics card?
does it have vdpau capability? probably 8000 series and newer?
did you compile your nvidia drivers yourself? or install from a repository?
what version of the drivers are you using?

Add this repository.
Index of /repositories/X11:/Drivers:/Video/openSUSE_11.2
You will then find libvdpau.