I've tried this cause I pay for the mlb.tv season pass. First of all, you have to be on WiFi (or 4G?). You log in at mlb.tv and then it'll launch the flash player. Takes a little while to load up and seems sluggish. Audio comes through fine without hiccups, but the video leaves a lot to be desired. We're talking maybe 2-3 frames per second.
I've noticed that most flash apps seems herky jerky, so there's hope that as Adobe optimizes Flash for android, things might get better.
But I can confirm that this definitely "works".