I've never seen them play live, but I know someone who has and he said they were amazing!
I have their Live at Slane Castle DVD, picked that one up for a buck in China. That gig starts off with an amazing jam before ripping into "Can't Stop", one of my least favorite Peppers songs. I did a search for them on youtube and it appears that they usually start shows with an intro jam. Here are a few those jams. Enjoy.
FUJI ROCK FESTIVAL 06
Video from Green Fest in Indjija,Serbia, 26/06/2007.
From Live at Slane Castle.Click here to buy.