I'm sure that some people have already encountered this problem or run across it on their own, but due to some format changes, telecasts of baseball games that were downloaded through MLB.com in 2006 are not viewable anymore.
Instead of me getting out of my depth and trying to understand the intricacies of digital rights management (DRM, and I'm darn proud I knew what that stood for), I would refer you to this post from The Joy of Sox, which does the best job of explaining the issue.
I've only bought one game to download in my life which was the Dodgers 2004 NL West clinching game. Which I found out I could only view on a PC at the time. And my PC was getting old and I was about to give it away. I don't think I ever watched the game a second time.
MLB.com's superior customer service, which rivals that of an East German grocery store in 1975, is right on top of the case it appears.