Why do some composers gesticulate wildly, while others reserve their composure?
https://www.youtube.com/watch?v=OoZdwam7wgw is based on just one piece, Mahler's Symphony 2, and a sample size of one from which we can't conclude anything. But I've noticed these wildly different levels of extroversion! Pierre Boulez, Mravinsky, Claudio Abbado tend to stay still and not make faces. Leonard Bernstein, Gustavo Dudamel usually gesture and jitter overzealously.