No XVideo support for Radeon HD 4200?

[george+freebsd at m5p.com]

> HP Compaq Presario CQ61-420US (dual core amd64)
> ATI Mobility Radeon HD 4200
I forgot to mention: FreeBSD 8.0-RELEASE, Xorg with no upgrades.
> Xorg starts and loads the extmod module with the the XVideo extension,
> and then a little later the radeon module, according to Xorg.0.log,
> but xvinfo says
> 
> X-Video Extension version 2.2
> screen #0
>  no adaptors present
> 
> Needless to say, this gives poor performance for mplayer and such
> programs.  What's going on?                      -- George Mitchell