It just hit me: no one mentioned LET THERE BE ROCK! Granted, it has not been officially released by AC/DC on DVD but it's the last full-length concert documented with Bon Scott just months before his demise. It has some audio/video synchronicity problems but it's well-worth searching for a VHS copy. I know there are some DVD bootlegs out there as well.
I haven't seen LET THERE BE ROCK since I was in high school! Beats the hell out of THE SONG REMAINS THE SAME that's for sure. Though in Zeppelin's defense, that live DVD box set they released some years back rules.
I think LTBR was recorded in Dec. 1979, 2 months before the great man left us. That said, the audio soundtrack's available on the Bonfire set.