Recently I had to replace my video-capable phone with a Blackberry, and as luck would have it I got mine only days before the Blackberry that does video and audio came out. It was a tradeoff. My thumb hurts because the BB scroll wheel is a poor substitute for a touch screen. On the other hand, mail arrives quickly and I can use it as a wireless modem for my laptop.
Since my blackberry doesn't do video any more, I chose the Centon moVox 1GB for that. It's $50 delivered, plays mp4 videos and mp3 audio, and stores a gigabyte of info. You format it and drop files into it like a pen drive, and they play just fine. It charges from USB too. I've tried the methods previously described here for converting video, and they work just fine. Now I can store four two hour movies on it and a couple albums, and reserve my phone for other stuff.
You can't tell from looking at the Newegg description, but the thing is very small. It's about 1cm thick, 3cm wide and 4.5 cm tall. The buttons are not intuitive -- you have to play with them to figure out that ff+play = enter on the menus. The manual is no help -- it's an amusing example of engrish, and lacks even an identification of the buttons.
There is no output for external video -- this thing is strictly a microscreen player. If you're interested in a little recreational video in a pinch, though, it will do the trick. If you get one, don't forget to format it FAT. You can't store any media on it until you do. It comes in more expensive versions up to 8GB. I have no idea what battery life is, but after I've used it a while I'll update this post. As always, Newegg delivered promptly and as advertised. It's a lot more fun to just fire off an online order in the middle of the night than to burn a precious day and five gallons of gas wandering from (hopefully open!) store to store searching for something that might or might not be good.