We just told our kids no DVD for the plane.
The reason we're doing this is that we're keeping our carry-on "light". Knowing full well that the more carry-ons the slower the security check points. Plus there is the added bonus of another check at the gate, if everyone takes a carry-on (I know everyone is allowed), the lines will last forever. I'll carry-on one bag for the 4 of us. The only things in the bag will be travel documents, my ID, camera, cell phone, meds and we'll take the mp3 players and gameboys. I pack the meds in a clear ziplock bag, the electronics and chargers in a clear ziplock bag. Keeps everything organized in my bag and easy for the security checkers to go through. We'll check 3 bags, with some clothes for everyone in each bag....
Our kids are 11 & 13 and we have a 2.5 hr flight a 1 hr lay-over (hopefully) and then a 1hr flight. They can certainly make due with the MP3's and the gameboys. If I had younger kids I might feel differently. With all the security lines, flight delays, it might be an essential travel item

if you have younger children.