And it's not just that they were eaten by bears. The audio itself is six minutes long, during which Treadwell is alive and conscious while being gored, which means that the attack was neither quick nor painless. Treadwell's girlfriend tried to fight the bear off but failed, powerless to stop the bear from dragging Treadwell into the woods, and left alone by herself before the bear came back for her. Here's The Other Wiki's description of what was left of them (NSFW/NSFL): "The mangled remains of Treadwell and Huguenard were discovered quickly upon investigation. Treadwell's disfigured head, partial spine, and right forearm and hand, with his wrist watch still on, were recovered a short distance from the camp. Huguenard's partial remains were found next to the torn and collapsed tents, partially buried in a mound of twigs and dirt." It's the most horrific sort of death imaginable.
What's particularly scary about Herzog's reaction to the audio is the very quiet way he says, "Turn it off," when he's finally had enough. There's something artificial about his calm that seems to indicate he's trying very hard not to freak out. Werner Herzog is freaked out. Eventually you see tears coming from his eyes and his hands trembling from the tape.
To make the point clearer for those who do not know about Werner Herzog... well, we are talking about a guy who once during an interview got shot by an unseen sniper, and his response was to say, "It was not a significant bullet. I am not afraid." Among Herzog fans, this incident is considered the tip of the iceberg among his antics. And yet this Crazy Awesome man who's Made of Iron was visibly shaken by the audio record. And he sternly and calmly advised/insisted that the tape to be destroyed.
And the executives wanted the actual audio played in the movie itself.
Some of Treadwell's rants can be a bit disturbing at times. Some rants that come to mind are the ones involving poachers and a particular instance where he's in his tent and starts yelling for various deities (God, Allah, and some Hindu gods) to send rain and end a drought that's afflicting the animals he loves so much. While it's not always the content that's disturbing, his general demeanor can be unsettling; at some points he appears to be emotionally unstable (exhibiting wild mood swings) and extremely paranoid (his ex-girlfriend claims he was bi-polar and refused to take his medication). Can double as a Tear Jerker when you think about how badly he needed help and never got it.