I didn't see that program, don't get T.V. here. Shooting from above on a deer walking away and drop's it instantly; sounds like a neck shot. One heck of a shot but, if he had been off target just a bit either way or a breeze had blown the bullet off just a bit and ripped out a chunk of meat, would it still be on heck of a shot? We never hear about animals wounded with those shot's nor do we see to much of it. I'm well aware that there are a lot of shooter's capable of making shot's like that. But just as in your case it incourages people to try it themselves.
With today's cartridge's 300 yds is still a very long way but, properly zeroed in there are some that have a max point blank range way out there. I think that might make 300 yds reasonable, IF, the person doing it has access to three hundred yard ranges AND practices a lot at those ranges,AND practices at those range's in the field.
I also got from your post that they never used the range finder until after the shot. Go out and try to pick out an object at 450 yds. Measure it and see how close you come on a regular basis. Maybe I'm being a bit snooty but I deplore those kinds of shooting. Do you think that shot would have been taken at that range on a truely dangerious animal? I don't think so!