hi folks,
i've configured three Macs so that they can talk to my KnoppMyth backend:

1) LiveTV/recorded TV:
-as long as you configure mysql.txt on the Mac frontend correctly, this works. my mysql.txt looks like:
DBHostName=192.168.0.2
DBUserName=mythtv
DBPassword=mythtv
DBName=mythconverg
DBType=QMYSQL3

2) Video:
-in Utilities and Settings -- Setup -- Media Settings -- Video Settings -- Player Settings:
/Applications/MPlayerOSX2.app/Contents/Resources/mplayer.app/Contents/MacOS/mplayer -fs

of course, you must install Mplayer. Watch out for spaces in the name of Mplayer. When installed, it looks like:
"MPlayer OS X 2"
it should look like:
"MPlayerOSX2"
otherwise, it won't work.

Also, you must mount your video folder on the Mac in some fashion. My videos are stored on a Linux nfs server. I had to create /myth/video on the Mac (do this as root). Then I used NFSManager to create mount points on my Mac.

3) Playing DVDs:
-in Utilities and Settings -- Setup -- Media Settings -- DVD Settings -- General Settings -- Location of DVD device: /dev/rdisk1
-in Utilities and Settings -- Setup -- Media Settings -- DVD Settings -- Play Settings:
/Applications/MPlayerOSX2.app/Contents/Resources/mplayer.app/Contents/MacOS/mplayer dvd:// -dvd-device %d -fs

this will only play the DVD...no menus. Big Deal.

I could not get VLC to behave correctly in the context of the MythTV UI. It would not come to the foreground. MPlayer does this correctly (-fs). Any hints are greatly appreciated, since MPlayer doesn't do DVD menus, and there is no xine player for OSX that I can find.

Hope this helps!

-Bob K