I had to unsubscribe to the pile of junk that is mlb.tv. It's just too flaky to be worth the price.
I've heard that from other people as well. They rolled out the HD premium package this year and I guess it barely works.
It almost never works, and when it does, it's not "HD." It's just pretty decent quality. It's usually closer to Youtube quality. The video just randomly stops working all the time. The archives aren't put up in time, and they haven't even bothered to provide the condensed games yet (one of the reasons I subscribed). Sometimes the archives seem to be put up, but come up with a blackout message when you try to watch them. When this is pointed out they will either claim (1) No, they work fine, you're wrong, or (2) You're trying to watch an archive that doesn't exist (as if I give a shit what their internal problems are).
Even if everything did work right, the blackout restrictions suck hard. It's ludicrous to me that TV stations wouldn't want their feeds, and their advertisers, reaching more people.
Also, you need to install some stupid plug-in that (on both Mac and Windows) runs in the background at all times, and measurably eats up memory and processor time even when you're not watching any videos. (It actually installs itself as a Unix-style daemon on OS X, which is not the right approach for that kind of thing AT ALL.)
It's also the ugliest, more non-intuitive website ever. Plus live games, when they work, are super laggy. This makes gameday kinds of things not work.
There was about a week where they were being somewhat honest on their blog about their problems. But then all those posts were deleted.
I think it's great that they're trying to make games available, but I'm not about to give them a free pass when they're not doing it right.