TV placement above the fireplace is not optimal -- too high. You'll get a crinked neck from looking up at it after a while. Maybe ok in hotel lobbies, but not in a private home. Find another place.

I agree with haus proud. But if you insist on doing it, best thing is to put the DVD player and any other cable or DVR/TIVO box in a remote location with the connecting wires going through the walls (electricians can do this.) Or, I was just reading somewhere that what I just said is old technology, and now you can do these things wirelessly. However, I don't know anything more about the wireless option.

Hiding even a slim DVD player in the mantle is going to make for a mantle that's much too thick.

Try www.Farringtoncabinetworks.com Click on portfolio. There is a white surround that has a hidden cabinet.

I've been hearing the stuff about a "crinked neck" from having a tv above the fireplace. It's just not true, unless you have a small room where you're sitting really close which makes for a steep angle to look up at the screen. I have mine above the fireplace mantel and neither my family nor any friends have complained about it. The more important consideration is the heat that is produced by the fireplace. You need to make sure that your mantle shelf sticks out from the wall at least 8". This shields the unit from the rising heat. That's also the reason that putting your DVD or any other electronics on the shelf is not a good idea. Off to the side is okay. As the other poster said, you can run wires through the walls to where your equipment is. Hope this helps.