What do conductors do?

Music that involves coordinating a group of players or singers has always needed a timekeeper of some sort.

So what exactly does a maestro do? Are subtle musical cues really communicated to an orchestra by a leader's baton or hands or is it just showmanship? Or does a maestro reveal something extra in the music that the players in an orchestra might not discover for themselves?

Tay Kewei met with conductors from the SSO and SCO to find out how they translate their vision into the glorious sounds you hear.