On the box of the DMR-EH68 it says "Create your own JukeBox on HDD".
You can do this by copying or 'ripping' your cds onto the hard drive or copying MP3s froma USB device.
When ripping a CD, the audio is stored in LPCM (or WAV) quality and the unit uses it's own internal Gracenote database to populate song/album titles.
While copying a CD to the harddrive, no other recording or viewing operations can be performed and the copied files can't be copied to a USB or burnt to another disc.
Playing the music is easy enough but it limited in regards to playlists or anything similar if you are familiar withthe concept from any PC based music player.
The albums you have on disc are shown in a list and you select the one you want to play but there is very limited control over which album will be played next.
The order you rip the CDs into the hard drive is the order they are presented and then played sequentially, so if you have some Classical to calm the youngster before bed and some Sepultura for other occasions, you have to be quick to hit rewind or stop once the Classical stops, or delete your ripped collection and start again.
You can only sort the ripped collection by album name or ripped sequence, I haven't tried playing them in album order yet.
I've tried ripping Kings of Leon - Only the Night twice now and at least one song skips, (it plays normally with out skipping though), I can only rip an entire album instead of individual songs so have to delete the whole album and start again each time.
As far as MP3s go, you can only copy them from the USB socket. You can play CD's that have MP3s burnt on them, but you can't copy them to the hard drive, which is can be frustrating if you have a few burnt as backups but don't have the originals on your PC any more. Sure you can copy from disc to a USB pen drive on the laptop but it turns the exercise into a chore.
If you have DVDs with archived MP3s on them, the player declares the discs to be incompatible, you have to copy them to USB before you can use the DMR-EH68 as an audio source.
After the arduousness of storing the music and lower priority when recording video, it's like Panasonic thought "What else can we store on the DMR-EH68 as well as video" instead of "How would we use a JukeBox".