This video is about situational awareness more than density altitude. The two persons aboard are conducting animal counts. Not heard in this version is the continuous banter between the pilot and observer. There is a vastly superior digitalized copy of the video in which you can hear that incessant chatter. I've seen this video a number of times and always I felt that that amount of chatter + low level + mtn terrain = soon to come accident. It was horrifying to watch.
Notice in this version about 1 minute before impact the pilot steers to the left of a knoll. On the digital version he exclaims surprise (expletive) and that he better be more careful. The observer responds, "Yeah".
The wreckage was found several yrs later by hikers. Various items were recovered, including a VHS camcorder. The camera had come to rest outside the wreckage and had endured yrs of extreme weather. It required expert technicians to improve the video and sound quality.
I continue to believe that if the pilot had turned to the left at the ridge he would have probably made it. Incidently, that ridge is just that, a ridge. It is not a wall to a box canyon.