I only played through the story so i'm not sure how good this speedrun is but overall it looks quite good.
I got Legends to 100% and it's madness. Just beating nightmare survival solo is pretty much impossible unless you're some kind of a cyborg, and this guy doesn't lose a zone and hits all 5 side objectives on his way there.
Moon stance just to move faster around the stage, all kinds of crazy animation cancels and consistent headshot after headshot.
There is an exploit here where he plays a very specific Nightmare Survival by changing the date on his PS, they change every week with different stage modifiers and different enemies in every wave. Here - arrows deal more damage, also enemy arrows but he obviously doesn't get hit.
This goes to show how insanely OP the Hunter can be is in the right hands.