I just filmed my teammate doing this last night and thought I would share it.
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In addition to doing gymnastics, Michael is a world class armwrestler (3rd at World Championships a couple years ago in the 154 lbs weight class). Given his weight, these are one arm chin ups at about 122% bodyweight.
I don't think there are any videos of anybody one arm chinning carrying more weight than this on YouTube.
Please correct me if I'm wrong.