Mumble Server IP: mumble.mcpvp.com
Mumble is the Voice Chat client we use to chat while in-game. It's especially great for teaming up while on CTF or for raids in mcpvp, though a lot of players just use it for a friendly place to chat. You can download mumble from www.mumble.com.
Sorry about the gray screen for the first 35 seconds - you don't miss anything important, I promise - and I'm too lazy to re-record the whole video to fix it.