At the beginning of each fall semester in my introductory conducting course, we spend some time exploring and discussing what the act of conducting is--what it's about, how that's accomplished--in a fundamental sense. This involves several components like critical/comparative listening, body awareness exercises, expressive movement improvisation, and watching video.
I use video examples to show how conducting can be a whole-body, expressive act in collaboration with an ensemble of musicians, and that really exciting music-making can be the result (and that this idea is a fairly recent evolution of the conductor's role, as historical footage we view clearly demonstrates).
Two of my favorite examples each year continue to be Carlos Kleiber and Simon Rattle. Both are conductors with tremendous energy and charisma, who use their whole bodies extremely vividly and acheive remarkable engagement with their ensembles.
Kleiber, of course, is the conductor's conductor, whose video many conductors watch and study and generally nerd out about. He really is magnificently expressive and elegant, and his engagement with the players he leads is obvious. Notice, though, that he leads very strongly, and the flow of expressive effect generally is from conductor to players to listeners (aurally, that is. Visually, it's conductor to listeners too; there is no small element of drama and flourish in his work):
Rattle is similarly completely, charismatically engaged with his whole body, even moreso. What I love about his work that is distinctive, is that he feels much more like chief among collaborators. He receives as intently as he transmits, and the intensity of his listening and engagement with players makes connections with the audience more directly: he's less performer and more partner and proxy. It makes for a clear example of the evolution of the role of the conductor (in the conservative setting of the orchestra) in the 21st century (and also that all concert halls should have seating in the round like Berlin does, that's completely awesome):
Lots more video of both on Youtube.