@johnny:

This looks to be from BRT, which is Belgian national television; probably 1967 judging by the song and hair styles. And yes, an obvious lip sync--no cables on the guitars, no microphone for the singer (the biggest giveaway) AND a volume-slider fade out at the end! (Great the way you spotted the "ack!" too.)

These days, we have MTV--an entire channel dedicated to lip sync, but back then you could see it on all the channels from time to time. I'm always disappointed when I think I've found a rare, classic studio performance, only to find a bad lip sync instead. For example, I recently saw "The Kids Are Alright" (the Who) on DVD and was surprised how many of the clips were actually from lip synced TV shows like this one. Many musicians hate doing these things; I could easily imagine that Jimi was one of them.