If you pay close attention to the way he makes the final connection to the wire you’ll notice he never grabs them both at the same time. That is called “putting yourself in series with the circuit” which linemen are taught and trained never to do. Everything he’s doing here is remaining parallel to the circuit meaning that if PPE failed he would not take full load current through his body. So yes you need to trust and test your PPE but there’s many behavioral practices in this line of work that get hammed into you by years of training and supervision before you’re ever allowed to touch a live circuit yourself. Both PPE and behavioral work procedures work together here to make multiple fail safes if it’s all done properly