How do I determine if XvMC is compiled into my Kernel -- thanks?

That is part of X not the kernel to determine which you are using on Debian at least you need to look into the /etc/X11/XvMCConfig and you need the libxvmc1 package installed.

Thanks for the reply. I'm having difficulty understanding the directions from a post in mythtv_users group.

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I thought biniaries were compiled into the Kernel -- not applications.

Binaries are compiled for numerous things what they are telling you is that you need support for the XvMC when compiling mythtv probably with something like ./configure --with=xvmc as an option when configuring the program before make then make install. On Debian you would need the libxvmc-dev development package installed along with the xorg-dev I would think to have the header files needed when building packages that use them. You will need to figure out what these packages are called in your distro and use ./configure --help to show yourself exactly what the options are named as to pick the correct one or looking into the INSTALL or README file will usually tell you as well.

./configure --enable-xvmc (and if you have a Via Pro chipset) --enable-xvmc-pro --enable-xvmc-vld

And probably:
--enable-proc-opt

Cool