Yep, David was sadly killed in an Alouette while filming "High Road to China" in Yugoslavia. He was offered a lift in the helicopter after his Stampe suffered a tech problem - so was Tony Bianchi, but he stayed behind to fix the Stampe. The Alouette hit a cable as I recall.
I agree - superb film, have watched it quite a few times since acquiring it. Last year I walked the Seven Sisters cliffs between Eastbourne and Seaford and was imagining Spitfires and Me109s dogfighting down those valleys - then I saw David performing aeros exactly there on the video! Awesome!
The display at Biggin is excellent as well, just the right sort of music - must have been that year that he parted my hair with a low low inverted pass while I was pushing my bike past the end of the runway!