This is impressive, his total weighted pull up record is 310lbs, at 140lbs bodyweight.
Steven Proto holds the world record for weighted chin ups, at around 400lbs total (around 200lbs bodyweight).
I can't do pull ups with palms forward to compare to these guys (aggravates an old injury), I do them palms towards me, but I'm able to do abouit 350 total at 230 bodyweight (it's a bit easier though).
A 1 arm chin up is a goal for me but it's bloody hard, I think it's on a similar scale to a goal of a 150kg+ bench press.