I recently mounted an RCA media player by using the second partition on the device rather than the first...

for me this partition is /dev/sdb1 NOT /dev/sdb

so, basically...

sudo mkdir /media/mp3player

sudo mount -t /dev/sdb1 /media/mp3player
quite a simple solution, really

now leaves the question "what is the first partition then?"
I would assume that the first is a RAW partition containing the firmware of the player... definitely something that you'll wanna mount to mess with ; however, I don't think anyone will be able to get the partition going.