With my exploration of finding out everything about my little "ChIpod", I was looking for a way of replacing the battery/and or extending the play time. I saw the "minty Boost" and others--very creative--but who of us have that kind of time?
For about the same cost---you can do the following:
They now have a Female to female A type USB connector that you can get on {Fl}eBay. About $5.00. My MPx player has a different connection than what I've seen of late--really tiny vs. the standard phone USB connection cables.
Then do a search for USB charger on the same site [with those words]. You will find all sorts-- stick to the ones where you can use 2 AA's. I've read the 9V's aren't good for MP4's. I found one shipped for about $8.00.
Plug the USB output into the female connector and the usb connection to your MPxplayer to the other female end of the connector and Viola! Didn't even have to break a sweat. This can also be a way of not having to replace that battery in there if it's a soldered one--can be a permamnent power source if you use rechargeable batteries.
Soon to come---how tomake tthe most of your player as a movie machine--and why cutting and pasting new material [or dragging and dropping] doesn't work and why it becomes corrupt, along with all of my favorite freeware programs to go along with it.
Cheers!

mp4girl