OK, so you know where I'm coming from, I an a paleo-Firesign Fan. Meaning that I adored and still listen to the first four albums, and all the newly discovered radio shows from that era, up to the time this movie was made. So you're not going to hear any criticism of Firesign itself from me - at least, not of that period.
The original uncut audio tape of this live show is floating around the Internet, and is absolutely essential to understanding the piece, because (rant alert) the film itself is basically unwatchable because of the EXTREMELY bad editing and student-film-level production. Whether they were trying to shorten it drastically, or be creative, or whatever, it really, really doesn't work. Punch lines are left out, continuity purposely hacked to pieces, and whole sections of this extremely funny show are simply not there, while other questionable sections (Phil Austin singing) are left in. The overall effect is amateurish in the extreme.
So, it's basically good for seeing video of SOME of the highlights of the show, but the feeling you're left with is wanting to slap the director and editor. It's a real shame, because this is the Firesign Theatre at their best, right before they let personal differences destroy their vibe forever. If you're a Firesign fan, this is a must-own tape, but DON'T use this to acquaint others with the group - it's so hacked to pieces as to be impossible to follow. What a shame they didn't have access to a more professional film crew.