Most video mp3 players out in the market have internal batteries. So it would be really hard to a video mp3 that is an AA or AAA powered. plus most mp3's that are powered with AA/AAA have lower storage around 1-4 Gb.
Sorry but there isn't one out there.
I'm looking for a video mp3 player for my son. He's very big into the outdoors and such and so I'd like it to be AA or AAA powered, as he's not always near a computer to charge it back up. I'd prefer something with a large storage capacity, though something with SD or similar slots would work as well. Anything someone can point me in the direction of would be greatly appreciated.