Here's an easy way to watch MLB games live without having to pay for the MLB subscription.
Go here and download the NexDef plugin.
This stage only needs to be done once.
Now go here: HD Lounge
This will give you the schedule of games and which channel they are on - and you can click the desired channel to load it.
I've found the streams are excellent quality, but you occasionally need to reload the page a few times for it to work.