Endless Summer TV Special

[summerinparadise.flac]

I'm watching this on youtube and I'm having difficulty finding much info about this. Its quite enjoyable especially in comparison that other tv concert with all the guests + bad scripting.
My questions:
-How much of this is actually live? I notice Mike missing some notes on Surfing USA and theres no obvious Knebworth-ing of those notes. 
-The acoustic stuff: how much of this is scripted?  Obviously there must have been some but the exchanges between members seem quite realistic (see Al Jardine's reaction to when asked about his Surfin' story).
-What was Brian's involvement? He would have obviously been under the care of Landy but doesn't seem to be out of it or wired like he would be in post Brian Wilson 88 media.