Thanks Butch.
I was on the phone with mlb for a few minutes this afternoon.  The lady 
told me to go to the system requirements and make sure I had flash 
player and silverlight installed and mediaplayer (although I don't 
think mediaplayer is used if you have silverlight).  
I now have the games playing although there are no buttons showing up on 
the mlb media player page. There are also a few annoying yes/no prompts 
which you need to respond to before the audio will start.

On the faq page (or maybe in the system requirements) it says you can 
use mediaplayer 9 or below.  This is in fact the case as I tried it on 
my wife's computer with mediaplayer 9 and no silverlight.  
Maybe I should think about downgrading my mediaplayer and dumping 
silverlight.

For me, adobe flash player was the missing piece.

73 Chris