Hi Heather,
I checked the WDW website. Items that may not be brought into the theme parks include but are not limited to:
* Items w/ wheels, such as:
* Wagons
* Skateboards
* Inline skates
* Shoes w/ built-in wheels
* Strollers larger than 36" x 52"
* Suitcases, coolers or backpacks w/ or w/o wheels larger than 24" long x 15" wide x 18" high. Coolers required for medications may be stored in a locker or at Guest Relations.
* Any trailer-like object that is pushed or towed by an ECV, wheelchair or stroller.
* Alcoholic beverages
* Folding chairs
* Glass containers (excluding baby food jars & perfume bottles)
* Pets (unless they are service animals)
In addition, Animal Kingdom prohibits balloons, straws & drink lids due to the safety of the wildlife.
I've often toyed with the thought of bringing a portable DVD player to keep my boys entertained while waiting in line & especially while we're waiting for the parades & fireworks. Luckily, we've always been able to keep them entertained without one.
Here's a couple of things to think about before deciding to bring one in or not: DVD players aren't light & can get heavier as the day wears on & you become more tired. The batteries may go dead before you really need it the most waiting for nighttime parades. Its one more thing you'll have to keep up with & an expensive item that you may not want to risk being stolen or damaged during the day. If you have an iPhone, iPod touch etc., you may consider downloading a digital movie file a more doable option. Wishing you many magical memories :-)