Best tablet for just video, for car/kids

[TheSiege]

I want one for the back of the car, preferably 10in and can be powered by USB and can handle running 1080p content, not necessarily at 1080p but can run MKV files just fine. The brighter the better and the better sound the better. Must have memory expansion for media.
oh, and cheap.

Musts:
Memory Card Slot
USB Powered
Run 1080p content

Would like:
10in+
Bright
Loud