For a band with high standards, a perfect show is impossible, and an excellent show is rare. You hope that the norm is "good." To deliver a really exceptional, comfortable performance before a recording truck or film crew has been our unfulfilled dream of many years. Always it seemed that as soon as the machines started rolling, we forgot how to play and our equipment forgot how to work. Any tiny inaccuracy seemed magnified to staggering immensity by an internal vision of spinning tape-reels, malevolent machinery capturing that damned millisecond forever. But for these two nights the gods smile. And the film becomes not just a concert, but a symbol - for the band a scrapbook, and autobiography, an era frozen in glacial clarity. For the audience, it can be an enduring souvenir, and if it can't quite capture what it was like to be there, it is a way of seeing through many pairs of eyes, of shifting one's vantage-point around and above the players in a way no mortal could.