dvd player options for kids?

There really are a lot of options. If all of your video is in xvid format, they do sell portable DVD players that read divx and sometimes even xvid directly from CD-R and on some models also from USB and SD memory. I don't see a portable DVD player *by itself* in the car as a practical solution though, it would either have to be 1. held in lap (not good for a 3 yr old) 2. strapped in somehow (on center console armrest between seats? Or if the screen has a great enough folding angle you might be able to arrange it in the pocket on the back of a front seat but would be loose and potential projectile in a rollover accident) or 3. video out on portable DVD connected to a screen in the car such as cieling mounted or head rest screen.

The wiring for a headrest screen can be run through the headrest post and should not cause any safety issues... if we were talking about a 2010 Prius with an active headrest, maybe, but still not likely to cause any functional safety issues if securely mounted. If you are concerned about security and a headrest screen being stolen, you could put an inexpensive cover over the headrest when it's not in use so it would not be so obvious. You could also use a screen that securely straps onto the headrest so you can just strap it on when traveling and take it out at the end of the trip. In this case it would be best to use a video iPod or portable DVD player to plug into the screen. That would be easier I think than having to run wires under the seats and carpets and installing a DVD player in the slot in the dash that would likely only play DVD discs.

I would also not prefer the dash mounted fold out screen... From previous attempts posted here on PC, it looks like because of the rounded shape of the dash the screen can not fold to a proper angle to be viewable unless the unit is sticking out a ways from the dash, meaning you can no longer close the door to hide the fold out screen unit unless you just don't mount it securely so it can slide in and out a little, which would make it even easier to steal...

Setup 1: If I were looking to have a setup that will not cause any alterations to the car, the entire system can be installed or removed from the car in just a few quick minutes (easily removed or hidden from view to prevent theft) I would get a screen that can strap onto the headrest and play video from a portable DVD player (divx/xvid portable DVD player) or a video iPod.

Setup 2: If I were looking for a permanent solution that would cause alterations to the car that would be difficult or impractical/impossible to reverse, I would have headrests installed with screens (I don't like the ceiling mount option, could cause rear view issues for the driver becoming a safety concern, especially with larger screens) with power/video wires run through the headrest posts and a player installed in the dash slot.

Example for Setup 1 (my preference):
Mustek MP100 portable DVD player on Newegg looks like it might be able to play xvid and divx from CD, USB or SD for $150
Clarion VMA770 7" screen with "universal headrest bracket" (maybe more secure than straps? But should still be just as quick and easy to install/remove any time) on Newegg for $250
Total = $400
Just take the screen off and put it and the portable DVD player in the glovebox, center console or underfloor cargo bin to hide from view and deter theft and remove from the car completely when not needed. That would definitely be the quickest/easiest option and least likely to be stolen. Just connect the video to the screen and headphone jack to Aux jack in center console (as I presume a 3 yr old can't wear headphones). The DVD player should be able to be secured somewhere in the car during travel so it won't become a projectile in an accident and the screen should remain safe and secure mounted to the headrest. This sounds like a safe, secure, easy install option and not to mention not extremely expensive... and no file conversion necessary.