Of those claiming handball, do you jump with your arms by your side?
The guidance we are given hear in England that a 'natural' position does not always mean down by your side for this reason.
In my opinion (and remember as refs we all have a different perspective on certain incidents) he is making himself bigger in this particular clip.
I'm not saying I expect players to jump up like seals but that arm is away from his body, he could easily have jumped by putting his right arm on his left shoulder and tucked in. I just tried it and it doesn't affect my balance at all.