64 Connection

Is there a networking server for unity that can connect 64 players to do 32 vs 32 battles online?

Photon, SlimNet, uLink, ElectroServer and Smartfox can all do this

Thanks

Unity networking can do it too if you know what you do.
If you don’t know what you do likely all 6 will fail misserably

How do you use the unity networking?

http://unity3d.com/support/resources/tutorials/iphone-multiplayer-tutorial
http://unity3d.com/support/resources/example-projects/networking-example
http://docs.unity3d.ru/Tutorials/M2H_Networking_Tutorial/M2H_Networking_Tutorial_Original.pdf

Is there a video tutorial on how to use the network in unity?

No

And it wouldn’t help as you need to understand how networking works and thats nothing you will learn in 20mins unless you have a serious background in it.
Better experiment with the networking example project that you can find if you follow the resources link at the top to the example projects