Let's see how long this video is up! Here is Zeppelin performing "Kashmir" at the O2 Arena, London, on Monday, Dec. 10. "Kashmir" is the song most Led Zeppelin fans said they wanted to hear in a music magazine poll. This performance of it left Robert Plant in tears (according to this review). Has there ever been a more majestic rock song?? I don't think so.
In the likely event that video is removed, and it's uploader executed, here's a live performance from 1979 (with John Bonham):