Bugmenot-User , if i'm not wrong, the US radio broadcasting range is 88-108MHz. 76.8MHz lies in the TV broadcasting range (Channels 5-6). More info about the frequency range
Here.
So technically, tuning in to 76.8MHz, you'll be actually receiving TV broadcast signals. But due to the player's FM chip unable to demodulate the incoming signal, you'll just hear a bunch of static noises.
Japan uses a different set of frequency range, so their radio receiver are of different range as compared to the rest of the world. For whatever reason, i don't know..