You ever try google docs voice dictation? It is surprisingly good, I think they pushed an update recently. I know it isn't quite the same thing but it seems like such a solvable problem considering they have all the bits.

Youtube CC is hit or miss but sometimes is perfect. I figure a narrow domain like live sports is immanently solvable. Maybe it is time to promote audio captchas. Hmm. This is a bummer, thank you for sharing, would not have guessed.