Doubletwist failed to install on mine, I assumed it did not support JB. I don't have my tablet with me at work, or I'd post the exact error.
I just drag and drop media, however, every file I move; MP3, FLAC, MP4, AVI, WMA, gives me a warning that the format is unsupported and may not play on the device. They all do, but the warning is a PIA.
Clearly I'm missing something.